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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

For the fiscal year ended December 31, 2005

OR

Commission file number 1-5975

HUMANA INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (502) 580-1000

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  þ    No  ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    Yes  ¨    No  þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  þ    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  þ

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer or a non-accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act: (Check one):

Large accelerated filer þ        Accelerated filer ¨        Non-accelerated filer ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  þ

The aggregate market value of voting stock held by non-affiliates of the Registrant as of June 30, 2005 was $6,396,835,252 calculated using the average price on such date of $39.79.

The number of shares outstanding of the Registrant’s Common Stock as of January 31, 2006 was 163,485,922.

DOCUMENTS INCORPORATED BY REFERENCE

Parts I, II and III incorporate herein by reference portions of the Registrant’s Proxy Statement to be filed pursuant to Regulation 14A covering the Annual Meeting of Stockholders scheduled to be held April 27, 2006.

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HUMANA INC.

INDEX TO ANNUAL REPORT ON FORM 10-K

For the Year Ended December 31, 2005

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PART I

General

Headquartered in Louisville, Kentucky, Humana Inc., referred to throughout this document as “we,” “us,” “our,” the “Company” or “Humana,” is one of the nation’s largest publicly traded health benefits companies, based on our 2005 revenues of $14.4 billion. We offer coordinated health insurance coverage and related services through a variety of traditional and Internet-based plans for employer groups, government-sponsored programs, and individuals. As of December 31, 2005, we had approximately 7.1 million members in our medical insurance programs, as well as approximately 1.9 million members in our specialty products programs. We have approximately 559,000 contracts with physicians, hospitals, dentists, and other providers to provide health care to our members. During 2005, 51% of our premiums and administrative services fees were derived from contracts with the federal government, including 17% related to our TRICARE contracts and 20% related to our contracts in Florida with the Centers for Medicare and Medicaid Services, or CMS. Under our CMS contracts in Florida, we provide health insurance coverage to approximately 295,400 members as of December 31, 2005.

We were organized as a Delaware corporation in 1964. Our principal executive offices are located at 500 West Main Street, Louisville, Kentucky 40202, and the telephone number at that address is (502) 580-1000.

This Annual Report on Form 10-K contains both historical and forward-looking information. See Item 1A.—Risk Factors for a description of a number of factors that could adversely affect our results or business.

Business Segments

We manage our business with two segments: Government and Commercial. The Government segment consists of members enrolled in government-sponsored programs, and includes three lines of business: Medicare Advantage, TRICARE, and Medicaid. The Commercial segment consists of members enrolled in products marketed to employer groups and individuals, and includes three lines of business: fully insured medical, administrative services only, or ASO, and specialty. We identified our segments in accordance with the aggregation provisions of Statement of Financial Accounting Standards (SFAS) No. 131, Disclosures About Segments of an Enterprise and Related Information, or SFAS 131, which is consistent with information used by our Chief Executive Officer in managing our business. The segment information aggregates products with similar economic characteristics. These characteristics include the nature of customer groups and pricing, benefits and underwriting requirements.

The results of each segment are measured by income before income taxes. We allocate all selling, general and administrative expenses, investment and other income, interest expense, and goodwill, but no other assets or liabilities, to our segments. Members served by our two segments often utilize the same medical provider networks, enabling us to obtain more favorable contract terms with providers. Our segments also share overhead costs and assets. As a result, the profitability of each segment is interdependent. We believe our customer, membership, revenue, and pretax income diversification across segments and products allows us to increase our chances of success.

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Our Products

The following table presents our segment membership, premiums and ASO fees by product for the year ended December 31, 2005:

Our Products Marketed to Government Segment Members and Beneficiaries

Medicare Advantage Products

Medicare is a federal program that provides persons age 65 and over and some disabled persons under the age of 65 certain hospital and medical insurance benefits. Hospitalization benefits are provided under Part A, without the payment of any premium, for up to 90 days per incident of illness plus a lifetime reserve aggregating 60 days. Eligible beneficiaries are required to pay an annually adjusted premium to the federal government to be eligible for physician care and other services under Part B. Beneficiaries eligible for Part A and Part B coverage under traditional Medicare are still required to pay out-of-pocket deductibles and coinsurance. CMS, an agency of the United States Department of Health and Human Services, administers the Medicare program.

We contract with CMS under the Medicare Advantage program to provide health insurance benefits to Medicare eligible persons under health maintenance organization, or HMO, preferred provider organization, or PPO, and Private Fee-For-Service, or PFFS, plans in exchange for contractual payments received from CMS, usually a fixed payment per member per month. With each of these products, the beneficiary generally receives benefits in excess of traditional Medicare, typically including a prescription drug benefit, a reduced monthly Part B premium, or reduced cost sharing. Beginning in 2006, Medicare beneficiaries have more health plan options, including a prescription drug benefit option and greater access to a PPO offering with the roll-out of Regional

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PPO plans. Prior to 2006, PPO plans were offered on a local basis only. Most Medicare Advantage plans must offer the prescription drug benefit as part of the basic plan, subject to cost sharing and other limitations. Medicare Advantage plans may charge beneficiaries monthly premiums and other copayments for Medicare-covered services or for certain extra benefits.

Our Medicare HMO and PPO plans, which cover Medicare-eligible individuals residing in certain counties, may eliminate or reduce coinsurance or the level of deductibles on many other medical services while seeking care from participating in-network providers, or in emergency situations. Except in emergency situations, HMO plans provide no out-of-network benefits. PPO plans carry an out-of network benefit that is subject to higher member cost-sharing. In many cases, these beneficiaries also may be required to pay a monthly premium to the HMO or PPO plan, in addition to the monthly Part B premium they are required to pay the Medicare program.

Our Medicare PFFS plans, which cover eligible Medicare beneficiaries in certain states, have no preferred network. Individuals in these plans pay us a monthly premium to receive enhanced prescription drug benefits and have the freedom to choose any health care provider that accepts individuals at reimbursement rates equivalent to traditional Medicare payment rates.

Medicare uses monthly rates per person for each county to determine the fixed monthly payments per member to pay to managed care plans. In the last decade, Congress has made several changes to how CMS must calculate these rates. The old (pre-1998) methodology was based on the Adjusted Average Per Capita Cost methodology, or AAPCC. Under AAPCC, CMS projected average county-level fee-for-service spending for the coming year to set the fixed monthly payments for Medicare health plans at 95 percent of the full AAPCC amount.

Under the AAPCC system, payment rates per county varied widely. For example, the 1997 payment rate for beneficiaries 65 and older for Part A and Part B services ranged from a low of $220.92 in Arthur County, Nebraska to a high of $767.35 in Richmond County, Staten Island, New York. Some states saw differences of more than 20 percent between adjacent counties. Since county fee-for-service costs were used to estimate county managed care payment rates, the rates reflected differences among counties and regions in fee-for-service utilization patterns and cost structures.

In the Balanced Budget Act of 1997 (BBA), Congress created a new rate-setting methodology, eliminating the direct link in the AAPCC method between managed care rates and local fee-for-service costs. As a result, the wide disparities in county payment rates were reduced, bringing all payment rates closer to the national average.

Additionally, the BBA required CMS to implement a risk adjustment payment system for Medicare health plans. Risk adjustment uses health status indicators to improve the accuracy of payments and establish incentives for plans to enroll and treat less healthy Medicare beneficiaries. CMS initially phased-in this payment methodology with a risk adjustment model that based payment on principal hospital inpatient diagnoses, as well as demographic factors such as gender, age, and Medicaid eligibility. From 2000 to 2003, risk adjusted payment accounted for only 10 percent of Medicare health plans payment, with the remaining 90 percent being based on demographic factors.

Pursuant to the Benefits and Improvements Protection Act of 2000 (BIPA), CMS implemented a new risk adjustment model that uses additional diagnosis data from ambulatory treatment settings (hospital outpatient department and physician visits). CMS has also redesigned its data collection and processing system to further reduce administrative data burden on Medicare health plans. In 2005, the portion of risk adjusted payment was increased to 50 percent, from 30 percent in 2004. The phase-in of risk adjusted payment will be increased to 75% in 2006 and to 100% in 2007. Under the new risk adjustment methodology, all managed care organizations must capture, collect, and submit the necessary diagnosis code information to CMS within prescribed deadlines.

Commensurate with phase-in of the new risk-adjustment methodology, payments to Medicare Advantage plans have been increased by a “budget neutrality” factor. The budget neutrality factor was implemented to prevent overall health plan payments from being reduced during the transition to the new risk-adjustment

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payment model. The payment adjustments for budget neutrality were first developed in 2002 and began to be used with the 2003 payments.

The budget neutrality adjustment will begin phasing out in 2007 and will be fully eliminated by 2011. This does not mean, however, that the aggregate per-member payments to Medicare plans will be reduced. As plans enroll less healthy beneficiaries, the need for the budget neutrality adjustment declines as the underlying risk adjusted Medicare rates paid to plans increase to account for their enrollees’ greater healthcare needs. As a result of changes in the CMS payment processes, including the phasing in of the risk adjustment methodology and the phasing out of the budget neutrality adjustment described previously, our CMS payments per member may change materially, either favorably or unfavorably.

At December 31, 2005, we provided health insurance coverage under CMS contracts to approximately 557,800 Medicare Advantage members for which we received premium revenues of approximately $4.6 billion, or 32.2% of our total premiums and ASO fees for the year ended December 31, 2005. Under our contracts with CMS in Florida, we provided health insurance coverage to approximately 295,400 members. These contracts accounted for premium revenues of approximately $2.8 billion, which represented approximately 60.9% of our Medicare Advantage premium revenues, or 19.9% of our total premiums and ASO fees for the year ended December 31, 2005.

Our HMO, PPO and PFFS products covered under Medicare Advantage contracts with CMS are renewed generally for a one-year term each December 31 unless CMS notifies Humana of its decision not to renew by May 1 of the contract year, or Humana notifies CMS of its decision not to renew by the first Monday in June of the contract year.

Medicare Prescription Drug Products

On January 1, 2006, we began covering members in prescription drug plans, or PDPs, under Medicare Part D. For 2006 coverage, Medicare-eligible individuals may enroll between November 15, 2005 and May 15, 2006 in one of our three plan choices. These three plan choices, Standard, Enhanced and Complete, may vary in terms of coverage levels and out-of-pocket costs for premiums, deductibles and co-insurance with the Standard plan offering the minimum benefits mandated by Congress. Our bid amount generally represents the payment we receive from CMS. However, this payment is subject to adjustments and subsidies in order for Humana and CMS to share the risk associated with financing the ultimate cost of the health benefit. Further, the amount of the payment we receive from CMS is subject to the risk adjustment payment process previously described in order to take into account beneficiaries’ health status risk factors. Unlike our Medicare Advantage products, there is no phase-in of the risk adjustment payment process for our PDP products. Our PDP products covered under Medicare Part D contracts with CMS are renewed generally for a one-year term each December 31 unless CMS notifies Humana of its decision not to renew by May 1 of the contract year, or Humana notifies CMS of its decision not to renew by the first Monday in June of the contract year.

Medicare Presence

The following table sets forth the number of markets in which we sold our Medicare Advantage and PDP products as of January 1, 2006, as compared with January 1, 2005 and 2004:

In addition, we are marketing our HMO and PFFS products in Puerto Rico for coverage beginning January 1, 2006.

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Medicaid Product

Medicaid is a federal program that is state-operated to facilitate the delivery of health care services to low-income residents. Each electing state develops, through a state specific regulatory agency, a Medicaid managed care initiative that must be approved by CMS. CMS requires that Medicaid managed care plans meet federal standards and cost no more than the amount that would have been spent on a comparable fee-for-service basis. States currently either use a formal proposal process in which they review many bidders before selecting one or award individual contracts to qualified bidders who apply for entry to the program. In either case, the contractual relationship with a state generally is for a one-year period. Under these contracts, we receive a fixed monthly payment from a government agency for which we are required to provide health insurance coverage to enrolled members. Due to the increased emphasis on state health care reform and budgetary constraints, more states are utilizing a managed care product in their Medicaid programs.

Our Medicaid business, which accounted for approximately 3.8% of our total premiums and ASO fees for the year ended December 31, 2005, consisted of contracts in Puerto Rico, Florida and Illinois. Our 3-year Medicaid contracts with the Puerto Rico Health Insurance Administration, which accounted for approximately 2.8% of our total premium and ASO fees for the year ended December 31, 2005, were extended a fourth year and these contracts expire on June 30, 2006. We are preparing to bid on the new contracts that will be effective July 2006 although a request for such proposal has not yet been issued by the Puerto Rico Health Insurance Administration. At this time we are unable to predict the ultimate impact that any government policy decisions might have on our Medicaid contracts in Puerto Rico.

Our other current Medicaid contract, which is in Florida, is scheduled to expire on June 30, 2006. Due to Medicaid reform in Florida, we are currently negotiating the terms and rates for the renewal contract. We expect the current contract to be extended until August 31, 2006, and the subsequent renewal contract to be effective for a two-year term beginning September 1, 2006. Due to continual decreases in the reimbursement from the state of Illinois, we exited the Illinois Medicaid market effective July 31, 2005. The Illinois and Florida Medicaid contracts accounted for approximately 1.0% of our total premiums and ASO fees for the year ended December 31, 2005.

TRICARE

TRICARE provides health insurance coverage to the dependents of active duty military personnel and to retired military personnel and their dependents. Currently, three health benefit options are available to TRICARE beneficiaries. In addition to a traditional indemnity option, participants may enroll in an HMO-like plan with a point-of-service option or take advantage of reduced copayments by using a network of preferred providers.

We have participated in the TRICARE program since 1996 under contracts with the United States Department of Defense. Our current TRICARE South Region contract, which we were awarded in 2003, covers approximately 2.9 million eligible beneficiaries as of December 31, 2005 in Florida, Georgia, South Carolina, Mississippi, Alabama, Tennessee, Louisiana, Arkansas, Texas and Oklahoma. The South Region is one of the three regions in the United States as defined by the Department of Defense. Of these eligible beneficiaries, 1.1 million were TRICARE ASO members representing active duty beneficiaries, seniors over the age of 65 and beneficiaries in Puerto Rico for which the Department of Defense retains all of the risk of financing the cost of their health benefit. The TRICARE South Region contract is for a five-year period subject to annual renewals at the federal government’s option, with the third option period scheduled to begin April 1, 2006. We have subcontracted with third parties to provide selected administration and specialty services under the contract.

The TRICARE South Region contract contains provisions that require us to negotiate a target health care cost amount annually with the federal government. Any variance from the target health care cost is shared with the federal government. As such, events and circumstances not contemplated in the negotiated target health care

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cost amount could have a material adverse effect on our business. These changes may include, for example, an increase or reduction in the number of persons enrolled or eligible to enroll due to the federal government’s decision to increase or decrease U.S. military presence around the world. In the event government reimbursements were to decline from projected amounts, our failure to reduce the health care costs associated with these programs could have a material adverse effect on our business.

During 2004, we completed a contractual transition of our TRICARE business. On July 1, 2004, our Regions 2 and 5 contract servicing approximately 1.1 million TRICARE members became part of the new North Region, which was awarded to another contractor. On August 1, 2004, our Regions 3 and 4 contract became part of our new South Region contract. On November 1, 2004, the Region 6 contract with approximately 1 million members became part of the South Region contract. The members added with the Region 6 contract essentially offset the members lost four months earlier with the expiration of our Regions 2 and 5 contract. For the year ended December 31, 2005, TRICARE premium revenues were approximately $2.4 billion, or 16.9% of our total premiums and ASO fees.

Part of the TRICARE transition during 2004 included the carve out of the TRICARE Senior Pharmacy and TRICARE for Life program which we previously administered on as ASO basis. On June 1, 2004 and August 1, 2004, administrative services under these programs were transferred to another contractor. For the year ended December 31, 2005, TRICARE administrative services fees totaled $50.1 million, or 0.4% of our total premiums and ASO fees.

Our Products Marketed to Commercial Segment Employers and Members

Consumer-Choice Products

Over the last several years, we have developed and offered various commercial products designed to provide options and choices to employers that are annually facing substantial premium increases driven by double-digit medical cost inflation. These consumer-choice products, which can be offered on either a fully insured or ASO basis, provided coverage to approximately 371,100 members at December 31, 2005, representing approximately 11.7% of our total commercial medical membership as detailed below.

These products are often offered to employer groups as “bundles”, where the subscribers are offered various HMO and PPO options, with various employer contribution strategies as determined by the employer.

Paramount to our consumer-choice product strategy, we have developed a group of innovative consumer products, styled as “Smart” products, that we believe will be a long-term solution for employers. We believe this new generation of products provides more (1) choices for the individual consumer, (2) transparency of provider costs, and (3) benefit designs that engage consumers in the costs and effectiveness of health care choices. Innovative tools and technology are available to assist consumers with these decisions, including the trade-offs between higher premiums and point-of-service costs at the time consumers choose their plans, and to suggest ways in which the consumers can maximize their individual benefits at the point they use their plans. We believe that when consumers can make informed choices about the cost and effectiveness of their health care, a sustainable long term solution for employers can be realized. Smart products, which accounted for approximately 65.1% of enrollment in all of our consumer-choice plans as of December 31, 2005, only are sold to employers who use Humana as their sole health insurance carrier.

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Some employers have selected other types of consumer-choice products, such as, (1) a product with a high deductible, (2) a catastrophic coverage plan, or (3) ones that offer a spending account option in conjunction with more traditional medical coverage or as a stand alone plan. Unlike our Smart products, these products, while valuable in helping employers deal with near-term cost increases by shifting costs to employees, are not considered by us to be long-term comprehensive solutions to the employers’ cost dilemma, although we view this as an important initial interim step.

HMO

Our HMO products provide prepaid health insurance coverage to our members through a network of independent primary care physicians, specialty physicians, and other health care providers who contract with the HMO to furnish such services. Primary care physicians generally include internists, family practitioners, and pediatricians. Generally, the member’s primary care physician must approve access to certain specialty physicians and other health care providers. These other health care providers include, among others, hospitals, nursing homes, home health agencies, pharmacies, mental health and substance abuse centers, diagnostic centers, optometrists, outpatient surgery centers, dentists, urgent care centers, and durable medical equipment suppliers. Because the primary care physician generally must approve access to many of these other health care providers, the HMO product is considered the most restrictive form of a health benefit plan.

An HMO member, typically through the member’s employer, pays a monthly fee, which generally covers, together with some copayments, health care services received from, or approved by, the member’s primary care physician. We participate in the Federal Employee Health Benefits Program, or FEHBP, primarily with our HMO offering in certain markets. FEHBP is the government’s health insurance program for Federal employees, retirees, former employees, family members, and former spouses. For the year ended December 31, 2005, commercial HMO premium revenues totaled approximately $2.4 billion, or 17.1% of our total premiums and ASO fees.

PPO

Our PPO products, which are marketed primarily to commercial groups and individuals, include some elements of managed health care. However, they typically include more cost-sharing with the member, through copayments and annual deductibles. PPOs also are similar to traditional health insurance because they provide a member with more freedom to choose a physician or other health care provider. In a PPO, the member is encouraged, through financial incentives, to use participating health care providers, which have contracted with the PPO to provide services at favorable rates. In the event a member chooses not to use a participating health care provider, the member may be required to pay a greater portion of the provider’s fees.

As part of our PPO products, we offer HumanaOne, a major medical product marketed directly to individuals. We offer this product in select markets where we can generally underwrite risk and utilize our existing networks and distribution channels. This individual product includes provisions mandated by law to guarantee renewal of coverage.

For the year ended December 31, 2005, commercial and individual PPO premium revenues totaled approximately $3.6 billion, or 25.5% of our total premiums and ASO fees.

Administrative Services Only

We also offer ASO products to employers who self-insure their employee health plans. We receive fees to provide administrative services which generally include the processing of claims, offering access to our provider networks and clinical programs, and responding to customer service inquiries from members of self-funded employers. These products may include all of the same benefit and product design characteristics of our fully insured PPO, HMO or consumer-choice products described above. Under ASO contracts, self-funded employers

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retain the risk of financing substantially all of the cost of health benefits. However, most ASO customers purchase stop loss insurance coverage from us to cover catastrophic claims or to limit aggregate annual costs. For the year ended December 31, 2005, commercial ASO fees totaled $209.4 million, or 1.4% of our total premiums and ASO fees.

Specialty Products

We additionally offer various specialty products including dental, group and individual life, and short-term disability. At December 31, 2005, we had approximately 1.9 million specialty members, including 1.5 million dental members. For the year ended December 31, 2005, specialty product premium revenues were approximately $386.7 million, or 2.7% of our total premiums and ASO fees.

The following table summarizes our total medical membership at December 31, 2005, by market and product:

Provider Arrangements

We provide our members with access to health care services through our networks of health care providers with whom we have contracted, including hospitals and other independent facilities such as outpatient surgery centers, primary care physicians, specialist physicians, dentists and providers of ancillary health care services and facilities. We have approximately 559,000 contracts with health care providers participating in our networks, which consist of approximately 336,300 physicians, 3,600 hospitals, and 219,100 ancillary providers and dentists. These ancillary services and facilities include ambulance services, medical equipment services, home health agencies, mental health providers, rehabilitation facilities, nursing homes, optical services, and pharmacies. Our membership base and the ability to influence where our members seek care generally enable us to obtain contractual discounts with providers.

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We use a variety of techniques to provide access to effective and efficient use of health care services for our members. These techniques include the coordination of care for our members, product and benefit designs, hospital inpatient management systems and enrolling members into various disease management programs. The focal point for health care services in many of our HMO networks is the primary care physician who, under contract with us, provides services to our members, and may control utilization of appropriate services, by directing or approving hospitalization and referrals to specialists and other providers. Some physicians may have arrangements under which they can earn bonuses when certain target goals relating to the provisions of quality patient care are met. Our hospitalist programs use specially-trained physicians to effectively manage the entire range of an HMO member’s medical care during a hospital admission and to effectively coordinate the member’s discharge and post-discharge care. We have available a variety of disease management programs related to specific medical conditions such as congestive heart failure, coronary artery disease, prenatal and premature infant care, asthma related illness, end stage renal disease, diabetes, cancer, and certain other conditions.

We typically contract with hospitals on either (1) a per diem rate, which is an all-inclusive rate per day, (2) a case rate or diagnosis-related groups (DRG), which is an all-inclusive rate per admission, or (3) a discounted charge for inpatient hospital services. Outpatient hospital services generally are contracted at a flat rate by type of service, ambulatory payment classifications, or APCs, or at a discounted charge. APCs are similar to flat rates except multiple services and procedures may be aggregated into one fixed payment. These contracts are often multi-year agreements, with rates that are adjusted for inflation annually based on the consumer price index or other nationally recognized inflation index. Outpatient surgery centers and other ancillary providers typically are contracted at flat rates per service provided or are reimbursed based upon a nationally recognized fee schedule such as the Medicare allowable fee schedule.

Our contracts with physicians typically are renewed automatically each year, unless either party gives written notice to the other party of their intent to terminate the arrangement. Most of the physicians in our PPO networks and some of our physicians in our HMO networks are reimbursed based upon a fixed fee schedule, which typically provides for reimbursement based upon a percentage of the standard Medicare allowable fee schedule.

Capitation

For 4.4% of our December 31, 2005 medical membership, we contract with hospitals and physicians to accept financial risk for a defined set of HMO membership. In transferring this risk, we prepay these providers a monthly fixed-fee per member, known as a capitation (per capita) payment, to coordinate substantially all of the medical care for their capitated HMO membership, including some health benefit administrative functions and claims processing. For these capitated HMO arrangements, we generally agree to reimbursement rates that target a medical expense ratio ranging from 82% to 89%. Providers participating in hospital-based capitated HMO arrangements generally receive a monthly payment for all of the services within their system for their HMO membership. Providers participating in physician-based capitated HMO arrangements generally have subcontracted directly with hospitals and specialist physicians, and are responsible for reimbursing such hospitals and physicians for services rendered to their HMO membership.

For 7.8% of our December 31, 2005 medical membership, we contract with physicians under risk-sharing arrangements whereby physicians have assumed some level of risk for all or a portion of the medical costs of their HMO membership. Although these arrangements do include capitation payments for services rendered, we process substantially all of the claims under these arrangements.

Physicians under capitation arrangements typically have stop loss coverage so that a physician’s financial risk for any single member is limited to a maximum amount on an annual basis. We monitor the financial performance and solvency of our capitated providers. However, we remain financially responsible for health care services to our members in the event our providers fail to provide such services.

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Medical membership under these various arrangements was as follows at December 31, 2005 and 2004:

Capitation expense as a percentage of total medical expense was as follows for the years ended December 31, 2005, 2004 and 2003:

Accreditation Assessment

Our accreditation assessment program consists of several internal programs, including those that credential providers and those designed to meet the audit standards of federal and state agencies, as well as external accreditation standards. We also offer quality and outcome measurement and improvement programs such as the Health Plan Employer Data Information Sets, or HEDIS, which is used by employers, government purchasers and the National Committee for Quality Assurance, or NCQA, to evaluate HMOs based on various criteria, including effectiveness of care and member satisfaction.

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Physicians participating in our HMO networks must satisfy specific criteria, including licensing, patient access, office standards, after-hours coverage, and other factors. Most participating hospitals also meet accreditation criteria established by CMS and/or the Joint Commission on Accreditation of Healthcare Organizations, or JCAHO.

Recredentialing of participating providers occurs every two to three years, depending on applicable state laws. Recredentialing of participating physicians includes verification of their medical licenses; review of their malpractice liability claims histories; review of their board certifications, if applicable; and review of any complaints, including member appeals and grievances. Committees, composed of a peer group of physicians, review the applications of physicians being considered for credentialing and recredentialing.

We request accreditation for certain of our HMO plans from NCQA and the American Accreditation Healthcare Commission/Utilization Review Accreditation Commission, or AAHC/URAC. Accreditation or external review by an approved organization is mandatory in the states of Florida and Kansas for licensure as an HMO. Accreditation specific to the utilization review process also is required in the state of Georgia for licensure as an HMO or PPO. Certain commercial businesses, like those impacted by a third-party labor agreement or those where a request is made by the employer, may require or prefer accredited health plans.

NCQA performs reviews of standards for quality improvement, credentialing, utilization management, and member rights and responsibilities. We continue to maintain accreditation in select markets through NCQA.

AAHC/URAC performs reviews for utilization management standards and for health plan and health network standards in quality management, credentialing, rights and responsibilities, and network management. We continue to maintain URAC accreditation in select markets and certain operations.

Humana has also pursued ISO 9001:2000 certification over the past several years. ISO is the international standards organization, which has developed an international commercial set of certifications as to quality and process, called ISO 9001:2000.

Sales and Marketing

We use various methods to market our Medicare, Medicaid, and commercial products, including television, radio, the Internet, telemarketing, and direct mailings.

At December 31, 2005, we employed approximately 1,700 sales representatives, who are each paid a salary and/or per member commission, and used approximately 62,900 licensed independent brokers and agents to market our Medicare and Medicaid products in the continental United States and Puerto Rico. We also employed approximately 500 telemarketing representatives who assisted in the marketing of Medicare and Medicaid products by making appointments for sales representatives with prospective members. During 2005, we expanded the number of ways we market our Medicare products, including, among others, strategic alliances with Wal-Mart Stores, Inc., or Wal-Mart, State Farm^®, and USAA. The alliance with Wal-Mart includes stationing Humana representatives in the Wal-Mart stores, SAM’S CLUB locations and Neighborhood Markets across the country providing an opportunity to enroll Medicare eligible individuals in person.

Individuals become members of our commercial HMOs and PPOs through their employers or other groups which typically offer employees or members a selection of health insurance products, pay for all or part of the premiums, and make payroll deductions for any premiums payable by the employees. We attempt to become an employer’s or group’s exclusive source of health insurance benefits by offering a variety of HMO, PPO, and specialty products that provide cost-effective quality health care coverage consistent with the needs and expectations of their employees or members. We also offer commercial health insurance products to individuals.

At December 31, 2005, we used approximately 51,300 licensed independent brokers and agents and approximately 700 licensed employees to sell our commercial products. Many of our employer group customers are represented by insurance brokers and consultants who assist these groups in the design and purchase of health care products. We generally pay brokers a commission based on premiums, with commissions varying by market and premium volume. In addition to commission based directly on premium volume for sales to particular

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customers, we also have programs that pay brokers and agents on other bases. These include commission bonuses based on sales that attain certain levels or involve particular products. We also pay additional commissions based on aggregate volumes of sales involving multiple customers.

Risk Management

Through the use of internally developed underwriting criteria, we determine the risk we are willing to assume and the amount of premium to charge for our commercial products. In most instances, employer and other groups must meet our underwriting standards in order to qualify to contract with us for coverage. Small group laws in some states have imposed regulations which provide for guaranteed issue of certain health insurance products and prescribe certain limitations on the variation in rates charged based upon assessment of health conditions.

Underwriting techniques are not employed in connection with our Medicare, TRICARE, or Medicaid products because government regulations require us to accept all eligible applicants regardless of their health or prior medical history.

Competition

The health benefits industry is highly competitive. Our competitors vary by local market and include other managed care companies, national insurance companies, and other HMOs and PPOs, including HMOs and PPOs owned by Blue Cross/Blue Shield plans. Many of our competitors have larger memberships and/or greater financial resources than our health plans in the markets in which we compete. Our ability to sell our products and to retain customers may be influenced by such factors as those described on page 18 in Item 1A.—Risk Factors.

Government Regulation

Government regulation of health care products and services is a changing area of law that varies from jurisdiction to jurisdiction. Regulatory agencies generally have broad discretion to issue regulations and interpret and enforce laws and rules. The passing of the Medicare Modernization Act of 2003, or MMA, represents the most sweeping changes to Medicare since the BBA. Changes in applicable laws and regulations are continually being considered, and the interpretation of existing laws and rules also may change periodically. These regulatory revisions could affect our operations and financial results. Also, it may become increasingly difficult to control medical costs if federal and state bodies continue to consider and enact significant and sometimes onerous managed care laws and regulations.

Federal regulation

Medicare

The MMA made many significant changes to the Medicare fee-for-service and Medicare Advantage programs, as well as other changes to the commercial health insurance marketplace. Most significantly, the MMA created a voluntary prescription drug benefit, called “Part D” benefit, for Medicare beneficiaries beginning in 2006, established a new Medicare Advantage program to replace the Medicare+Choice program, and enacted tax-advantaged health savings accounts, or HSAs, for non-Medicare eligible individuals and groups. See the description of our Medicare products beginning on page 4 for additional discussion.

CMS conducts audits of plans qualified under its Medicare program at least biannually and may perform other reviews more frequently to determine compliance with federal regulations and contractual obligations. These audits include review of the plans’ administration and management, including management information and data collection systems, fiscal stability, utilization management and physician incentive arrangements, health services delivery, quality assurance, marketing, enrollment and disenrollment activity, claims processing, and complaint systems.

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CMS regulations require submission of quarterly and annual financial statements. In addition, CMS requires certain disclosures to CMS and to Medicare beneficiaries concerning operations of a health plan contracted under the Medicare program. CMS’s rules require disclosure to members upon request of information concerning financial arrangements and incentive plans between the plan and physicians in the plan’s networks. These rules also require certain levels of stop loss coverage to protect contracted physicians against major losses relating to patient care, depending on the amount of financial risk they assume. The reporting of certain health care data contained in HEDIS is another important CMS disclosure requirement.

Fraud and abuse laws

Enforcement of health care fraud and abuse laws has become a top priority for the nation’s law enforcement entities. The funding of such law enforcement efforts has increased dramatically in the past few years and is expected to continue. The focus of these efforts has been directed at participants in federal government health care programs such as Medicare, Medicaid, and the FEHBP. We participate extensively in these programs and have continued our stringent regulatory compliance efforts for these programs. The programs are subject to very technical rules. When combined with law enforcement intolerance for any level of noncompliance, these rules mean that compliance efforts in this area continue to be challenging.

Federal HMO Act

Of our nine licensed and active HMO subsidiaries as of February 1, 2006, eight are qualified under the Federal Health Maintenance Organization Act of 1973, as amended. To obtain federal qualification, an HMO must meet certain requirements, including conformance with benefit, rating, and financial reporting standards. Federal qualification allows us to participate in the FEHBP program. In certain markets, and for certain products, we operate HMOs that are not federally qualified because this provides greater flexibility with respect to product design and pricing than is possible for federally qualified HMOs.

Privacy regulations

The use of individually identifiable data by our business is regulated at federal and state levels. These laws and rules are changed frequently by legislation or administrative interpretation. Various state laws address the use and maintenance of individually identifiable health data. Most are derived from the privacy provisions in the federal Gramm-Leach-Bliley Act and the Health Insurance Portability and Accountability Act of 1996, or HIPAA. HIPAA includes administrative provisions directed at simplifying electronic data interchange through standardizing transactions, establishing uniform health care provider, payer, and employer identifiers and seeking protections for confidentiality and security of patient data. Violations of these rules could subject us to significant penalties.

State and local regulation

We are also subject to substantial regulation by the states in which we do business. We regularly are audited and subject to various enforcement actions by state departments of insurance. These departments enforce laws relating to all aspects of our operations, including benefit offerings, marketing, claim payments and premium setting, especially with regard to our small group business. Although any of the pending government actions could result in assessment of damages, civil or criminal fines or penalties, and other sanctions against us, including exclusion from participation in government programs, we do not believe the results of any of these actions, individually or in the aggregate, will have a material adverse effect on our financial position, results of operations, or cash flows.

Our Medicaid products are regulated by the applicable state agency in the state in which we sell a Medicaid product and by the Puerto Rico Health Insurance Administration, in conformance with federal approval of the applicable state plan, and are subject to periodic reviews by these agencies. The reviews are similar in nature to those performed by CMS.

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Laws in each of the states (including Puerto Rico) in which we operate our HMOs, PPOs and other health insurance-related services regulate our operations, including the scope of benefits, rate formulas, delivery systems, utilization review procedures, quality assurance, complaint systems, enrollment requirements, claim payments, marketing, and advertising. The HMO, PPO, and other health insurance-related products we offer are sold under licenses issued by the applicable insurance regulators. Under state laws, our HMOs and health insurance companies are audited by state departments of insurance for financial and contractual compliance, and our HMOs are audited for compliance with health services standards by respective state departments of health. Most states’ laws require such audits to be performed at least once every three years.

Our licensed subsidiaries are subject to regulation under state insurance holding company and Puerto Rico regulations. Certain of our subsidiaries operate in states that regulate the payment of dividends, loans, or other cash transfers to Humana Inc., our parent company, and require minimum levels of equity as well as limit investments to approved securities. The amount of dividends that may be paid to Humana Inc. by these subsidiaries, without prior approval by state regulatory authorities, is limited based on the entity’s level of statutory income and statutory capital and surplus. For additional information regarding our regulated subsidiaries’ statutory capital requirements see page 22 in Item 1A.—Risk Factors.

Audits and investigations

We are subject to various governmental audits, investigations, and enforcement actions as more fully described on page 24 in Item 1A.—Risk Factors.

Pending federal and state legislation

Diverse legislative and regulatory initiatives continue at both the federal and state levels to affect aspects of the nation’s health care system.

Our management works proactively to ensure compliance with all governmental laws and regulations affecting our business. We are unable to predict how existing federal or state laws and regulations may be changed or interpreted, what additional laws or regulations affecting our businesses may be enacted or proposed, when and which of the proposed laws will be adopted or what effect any such new laws and regulations will have on our financial position, results of operations or cash flows.

Other

Captive Insurance Company

We bear general business risks associated with operating our Company such as professional and general liability, employee workers’ compensation, and officer and director errors and omissions risks. Professional and general liability risks may include, for example, medical malpractice claims and disputes with members regarding benefit coverage. We retain certain of these risks through our wholly-owned, captive insurance subsidiary. We reduce exposure to these risks by insuring levels of coverage for losses in excess of our retained limits with a number of third-party insurance companies. We remain liable in the event these insurance companies are unable to pay their portion of the losses. In an effort to minimize credit risk, we insure our risks with a number of insurance companies having a long history of strong financial ratings. Since January 1, 2003, we have reduced the amount of coverage purchased from third-party insurance carriers and increased the amount of risk we retain based on the financial strength and liquidity of our captive insurance subsidiary. We provide a detail of the significant assets and liabilities as well as a rollforward of reserve activity related to our captive insurance subsidiary in Note 10 to the consolidated financial statements included in Item 8.—Financial Statements and Supplementary Data.

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Centralized Management Services

We provide centralized management services to each of our health plans and both of our business segments from our headquarters and service centers. These services include management information systems, product development and administration, finance, personnel, development, accounting, law, public relations, marketing, insurance, purchasing, risk management, internal audit, actuarial, underwriting, claims processing, and customer service.

Employees

As of December 31, 2005, we had approximately 18,700 employees, including 19 employees covered by collective bargaining agreements. We believe we have good relations with our employees and have not experienced any work stoppages.

This document includes both historical and forward-looking statements. The forward-looking statements are made within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995, and we are including this statement for purposes of complying with these safe harbor provisions. We have based these forward-looking statements on our current expectations and projections about future events, trends and uncertainties. These forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and assumptions, including, among other things, the information discussed below. In making these statements, we are not undertaking to address or update each factor in future filings or communications regarding our business or results. Our business is highly complicated, regulated and competitive with many different factors affecting results.

If the premiums we charge are insufficient to cover the cost of health care services delivered to our members, or if our estimates of medical claim reserves based upon our estimates of future medical claims are inadequate, our profitability could decline.

We use a significant portion of our revenues to pay the costs of health care services delivered to our members. These costs include claims payments, capitation payments, allocations of some centralized expenses and various other costs incurred to provide health insurance coverage to our members. These costs also include estimates of future payments to hospitals and others for medical care provided to our members. Generally, premiums in the health care business are fixed for one-year periods. Accordingly, costs we incur in excess of our medical cost projections generally are not recovered in the contract year through higher premiums. We estimate the costs of our future medical claims and other expenses using actuarial methods and assumptions based upon claim payment patterns, medical inflation, historical developments, including claim inventory levels and claim receipt patterns, and other relevant factors. We also record medical claims reserves for future payments. We continually review estimates of future payments relating to medical claims costs for services incurred in the current and prior periods and make necessary adjustments to our reserves. However, many factors may and often do cause actual health care costs to exceed what was estimated and used to set our premiums. These factors may include:

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Failure to adequately price our products or estimate sufficient medical claim reserves may result in a material adverse effect on our financial position, results of operations and cash flows.

If we do not design and price our products properly and competitively, our membership and profitability could decline.

We are in a highly competitive industry. Many of our competitors are more established in the health care industry in terms of a larger market share and have greater financial resources than we do in some markets. In addition, other companies may enter our markets in the future, including emerging competitors in the Medicare program and in consumer-choice health plans, such as high deductible health plans with HSAs. We believe that barriers to entry in many markets are not substantial, so the addition of new competitors can occur relatively easily, and customers enjoy significant flexibility in moving between competitors. Contracts for the sale of commercial products are generally bid upon or renewed annually. While health plans compete on the basis of many factors, including service and the quality and depth of provider networks, we expect that price will continue to be a significant basis of competition. In addition to the challenge of controlling health care costs, we face intense competitive pressure to contain premium prices. Factors such as business consolidations, strategic alliances, legislative reform and marketing practices create pressure to contain premium price increases, despite being faced with increasing medical costs. The commercial pricing environment, particularly in the 2 to 300 member groups, is extremely competitive. Several of our competitors, including public and not-for-profit companies, are pricing aggressively to gain market share.

Premium increases, introduction of new product designs, and our relationship with our providers in various markets, among other issues, could also affect our membership levels. Other actions that could affect membership levels include our possible exit from or entrance into Medicare or Commercial markets, or the termination of a large contract, including our TRICARE contract.

If we do not compete effectively in our markets, if we set rates too high or too low in highly competitive markets to keep or increase our market share, if membership does not increase as we expect, if membership declines, or if we lose accounts with favorable medical cost experience while retaining or increasing membership in accounts with unfavorable medical cost experience, our business and results of operations could be materially adversely affected.

If we fail to effectively implement our operational and strategic initiatives, our business could be materially adversely affected.

Our future performance depends in large part upon our management team’s ability to execute our strategy to position the Company for the future. This strategy includes opportunities created by the MMA. The MMA offers new opportunities in our Medicare programs, including our HMO, PPO, and PFFS Medicare Advantage

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products, as well as our PDP products. We have made substantial additional investments in the Medicare program to enhance our ability to participate in these expanded programs. We have doubled the size of our Medicare geographic reach since the enactment of the MMA through expanded Medicare product offerings. We are offering both the stand-alone Medicare Prescription Drug Coverage (PDP) and Medicare Advantage Health Plan with Prescription Drug Coverage (MA-PD) in addition to our other product offerings. Our Medicare presence as of February 1, 2006, included more than 700,000 Medicare Advantage members and approximately 1.7 million PDP members in 12 HMO markets, 33 local PPO markets, and 35 states in which we have a private fee-for-service offering. Enrollment in the new Part D prescription drug plans began on November 15, 2005, and the plans became effective January 1, 2006. We have been approved to offer the Medicare prescription drug plan in 46 states and the District of Columbia.

The timing of our new membership enrollment in our Medicare Advantage and PDP products is an important factor in meeting our business objectives. The pattern of quarterly earnings for 2006 is subject to certain assumptions including the timing of when a member enrolls in a plan, the plan type the member selects, and the speed with which the individual members meet their deductibles and cost-sharing provisions.

We have also made substantial investments in the service personnel and technology necessary to administer the growing Medicare business. Service issues intensified due to an enormous number of individuals being eligible in the new program on January 1. We have to implement various initiatives such as hiring additional service representatives to address the service issues.

The growth of our Medicare business is an important part of our business strategy. Any failure to achieve this growth may have a material adverse effect on our financial position, results of operations or cash flows. In addition, the expansion of our Medicare business in relation to our other businesses may intensify the risks to us inherent in the Medicare business, which are described elsewhere in this document. These expansion efforts may result in less diversification of our revenue stream.

Additionally, our strategy includes the growth of our Commercial segment business, with emphasis on our ASO and individual products, introduction of new products and benefit designs, including our Smart, consumer-choice products such as HSAs as well as the adoption of new technologies and the integration of acquired businesses and contracts.

There can be no assurance that we will be able to successfully implement our operational and strategic initiatives that are intended to position us for future growth or that the products we design will be accepted or adopted in the time periods assumed. Failure to implement this strategy may result in a material adverse effect on our financial position, results of operations and cash flows.

If we fail to properly maintain the integrity of our data, to strategically implement new information systems, or to protect our proprietary rights to our systems, our business could be materially adversely affected.

Our business depends significantly on effective information systems and the integrity and timeliness of the data we use to run our business. Our business strategy involves providing members and providers with easy to use products that leverage our information to meet their needs. Our ability to adequately price our products and services, provide effective and efficient service to our customers, and to timely and accurately report our financial results depends significantly on the integrity of the data in our information systems. As a result of our past and on-going acquisition activities, we have acquired additional information systems. We have been taking steps to reduce the number of systems we operate, have upgraded and expanded our information systems capabilities, and are gradually migrating existing business to fewer systems. Our information systems require an ongoing commitment of significant resources to maintain, protect and enhance existing systems and develop new systems to keep pace with continuing changes in information processing technology, evolving industry and regulatory standards, and changing customer preferences. If the information we rely upon to run our businesses

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was found to be inaccurate or unreliable or if we fail to maintain effectively our information systems and data integrity, we could have operational disruptions, have problems in determining medical cost estimates and establishing appropriate pricing, have customer and physician and other health care provider disputes, have regulatory or other legal problems, have increases in operating expenses, lose existing customers, have difficulty in attracting new customers, or suffer other adverse consequences.

We depend on independent third parties for significant portions of our systems-related support, equipment, facilities, and certain data, including data center operations, data network, voice communication services and pharmacy data processing. This dependence makes our operations vulnerable to such third parties’ failure to perform adequately under the contract, due to internal or external factors. We have recently changed vendors in our pharmacy benefits program. A change in service providers could result in a decline in service quality and effectiveness or less favorable contract terms which could adversely affect our operating results.

We rely on our agreements with customers, confidentiality agreements with employees, and our trade secrets and copyrights to protect our proprietary rights. These legal protections and precautions may not prevent misappropriation of our proprietary information. In addition, substantial litigation regarding intellectual property rights exists in the software industry. We expect software products to be increasingly subject to third-party infringement claims as the number of products and competitors in this area grows.

Our business plans also include becoming a quality e-business organization by enhancing interactions with customers, brokers, agents, and other stakeholders through web-enabling technology. Our strategy includes sales and distribution of health benefit products through the Internet, and implementation of advanced self-service capabilities, for internal and external stakeholders.

There can be no assurance that our process of improving existing systems, developing new systems to support our expanding operations, integrating new systems, protecting our proprietary information, and improving service levels will not be delayed or that additional systems issues will not arise in the future. Failure to adequately protect and maintain the integrity of our information systems and data may result in a material adverse effect on our financial positions, results of operations and cash flows.

We are involved in various legal actions, which, if resolved unfavorably to us, could result in substantial monetary damages.

We are a party to a variety of legal actions that affect our business, including employment and employment discrimination-related suits, employee benefit claims, breach of contract actions, and tort claims.

In addition, because of the nature of the health care business, we are subject to a variety of legal actions relating to our business operations, including the design, management and offering of products and services. These include and could include in the future:

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In some cases, substantial non-economic or punitive damages as well as treble damages under the federal False Claims Act, Rackateer Influenced and Corrupt Organizations Act and other statutes may be sought. While we currently have insurance coverage for some of these potential liabilities, other potential liabilities may not be covered by insurance, insurers may dispute coverage or the amount of our insurance may not be enough to cover the damages awarded. Additionally, the cost of business insurance coverage has increased significantly. As a result, we have increased the amount of risk that we self-insure, particularly with respect to matters incidental to our business. In addition, some types of damages, like punitive damages, may not be covered by insurance. In some jurisdictions, coverage of punitive damages is prohibited. Insurance coverage for all or some forms of liability may become unavailable or prohibitively expensive in the future.

A description of material legal actions in which we are currently involved is included under “Legal Proceedings” in Note 14 to the condensed consolidated financial statements included in Item 8.—Financial Statements and Supplementary Data. We cannot predict the outcome of these suits with certainty, and we are incurring expenses in the defense of these matters. Therefore, these legal actions could have a material adverse effect on our financial position, results of operations and cash flows.

As a government contractor, we are exposed to additional risks that could adversely affect our business or our willingness to participate in government health care programs.

A significant portion of our revenues relates to federal and state government health care coverage programs, including the Medicare, TRICARE, and Medicaid programs. Our Government Segment accounted for approximately 53% of our total premiums and ASO fees for the year ended December 31, 2005 and we expect the Government Segment to account for a greater percentage of our total premiums and ASO fees in 2006. These programs involve various risks, including:

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Our industry is currently subject to substantial government regulation, which, along with possible increased governmental regulation or legislative reform, increases our costs of doing business and could adversely affect our profitability.

The health care industry in general, and health insurance, particularly HMOs and PPOs are subject to substantial federal and state government regulation.

Our licensed subsidiaries are subject to regulation under state insurance holding company and Puerto Rico regulations. These regulations generally require, among other things, prior approval and/or notice of new products, rates, benefit changes, and certain material transactions, including dividend payments, purchases or sales of assets, intercompany agreements, and the filing of various financial and operational reports.

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Certain of our subsidiaries operate in states that regulate the payment of dividends, loans, or other cash transfers to Humana Inc., our parent company, and require minimum levels of equity as well as limit investments to approved securities. The amount of dividends that may be paid to Humana Inc. by these subsidiaries, without prior approval by state regulatory authorities, is limited based on the entity’s level of statutory income and statutory capital and surplus. In most states, prior notification is provided before paying a dividend even if approval is not required.

As of December 31, 2005, we maintained aggregate statutory capital and surplus of $1,203.2 million in our state regulated subsidiaries. Each of these subsidiaries was in compliance with applicable statutory requirements which aggregated $722.2 million. Although the minimum required levels of equity are largely based on premium volume, product mix, and the quality of assets held, minimum requirements can vary significantly at the state level. Given our anticipated premium growth in 2006 resulting from the expansion of our Medicare products, capital requirements will increase. We expect to fund these increased requirements with capital contributions from Humana Inc., our parent company, in the range of $450 million to $650 million in 2006.

Most states rely on risk-based capital requirements, or RBC, to define the required levels of equity. RBC is a model developed by the National Association of Insurance Commissioners to monitor an entity’s solvency. This calculation indicates recommended minimum levels of required capital and surplus and signals regulatory measures should actual surplus fall below these recommended levels. If RBC were adopted by all states and Puerto Rico at December 31, 2005, we would be required to fund $14.7 million in one of our Puerto Rico subsidiaries to meet all requirements. After this funding, we would have $378.2 million of aggregate capital and surplus above any of the levels that require corrective action under RBC.

The use of individually identifiable data by our business is regulated at federal and state levels. These laws and rules are changed frequently by legislation or administrative interpretation. Various state laws address the use and maintenance of individually identifiable health data. Most are derived from the privacy provisions in the federal Gramm-Leach-Bliley Act and HIPAA. HIPAA includes administrative provisions directed at simplifying electronic data interchange through standardizing transactions, establishing uniform health care provider, payer, and employer identifiers and seeking protections for confidentiality and security of patient data. The rules do not provide for complete federal preemption of state laws, but rather preempt all inconsistent state laws unless the state law is more stringent.

These regulations set standards for the security of electronic health information. Violations of these rules will subject us to significant penalties. Compliance with HIPAA regulations requires significant systems enhancements, training and administrative effort. HIPAA could also expose us to additional liability for violations by our business associates. A business associate is a person or entity, other than a member of the work force, who on behalf of a covered entity performs, or assists in the performance of a function or activity involving the use or disclosure of individually identifiable health information, or provides legal, accounting, consulting, data aggregation, management, administrative, accreditation, or financial services.

Another area receiving increased focus is the time in which various laws require the payment of health care claims. Many states already have legislation in place covering payment of claims within a specific number of days. However, due to provider groups advocating for laws or regulations establishing even stricter standards, procedures and penalties, we expect additional regulatory scrutiny and supplemental legislation with respect to claims payment practices. The provider-sponsored bills are characterized by stiff penalties for late payment, including high interest rates payable to providers and costly fines levied by state insurance departments and attorneys general. This legislation and possible future regulation and oversight could expose us to additional liability and penalties.

We are implementing a mail order pharmacy business that subjects us to extensive federal, state and local regulation. We are also subject to risks inherent in the packaging and distribution of pharmaceuticals and other health care products.

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We are also subject to various governmental audits and investigations. These can include audits and investigations by state attorneys general, CMS, the Office of the Inspector General of Health and Human Services, the Office of Personnel Management, the Department of Justice, the Department of Labor, the Defense Contract Audit Agency, and state Departments of Insurance and Departments of Health. Several state attorneys general and Departments of Insurance are currently investigating the practices of insurance brokers, including those of certain of the companies in the health care industry. All of these activities could result in the loss of licensure or the right to participate in various programs, or the imposition of fines, penalties and other sanctions. In addition, disclosure of any adverse investigation or audit results or sanctions could negatively affect our industry or our reputation in various markets and make it more difficult for us to sell our products and services.

Other areas subject to substantial regulation include:

In recent years, significant federal and state legislation affecting our business has been enacted. State and federal governmental authorities are continually considering changes to laws and regulations applicable to us and are currently considering regulations relating to:

All of these proposals could apply to us and could result in new regulations that increase the cost of our operations.

There can be no assurance that we will be able to continue to obtain or maintain required governmental approvals or licenses or that legislative or regulatory change will not have a material adverse effect on our business. Delays in obtaining or failure to obtain or maintain required approvals could adversely affect entry into new markets, our revenues or the number of our members, increase our costs or adversely affect our ability to bring new products to market as forecasted.

Our ability to manage administrative costs could hamper profitability.

The level of our administrative expenses impacts our profitability. While we attempt to manage effectively such expenses, increases in staff-related expenses, investment in new products, including our opportunities in the Medicare programs, greater emphasis on small group and individual health insurance products, acquisitions, and implementation of regulatory requirements, among others, may occur from time to time.

There can be no assurance that we will be able to successfully contain our administrative expenses in line with our membership that may result in a material adverse effect on our financial position, results of operations and cash flows.

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Any failure by us to manage acquisitions, and other significant transactions successfully could harm our financial results, business and prospects.

As part of our business strategy, we frequently engage in discussions with third parties regarding possible investments, acquisitions, strategic alliances, joint ventures, and outsourcing transactions and often enter into agreements relating to such transactions in order to further our business objectives. In order to pursue this strategy successfully, we must identify suitable candidates for and successfully complete transactions, some of which may be large and complex, and manage post-closing issues such as the integration of acquired companies or employees. Integration and other risks can be more pronounced for larger and more complicated transactions, or if multiple transactions are pursued simultaneously. If we fail to identify and complete successfully transactions that further our strategic objectives, we may be required to expend resources to develop products and technology internally, we may be at a competitive disadvantage or we may be adversely affected by negative market perceptions, any of which may have a material adverse effect on our results of operations, financial position or cash flows.

If we fail to develop and maintain satisfactory relationships with the providers of care to our members, our business could be adversely affected.

We contract with physicians, hospitals and other providers to deliver health care to our members. Our products encourage or require our customers to use these contracted providers. These providers may share medical cost risk with us or have financial incentives to deliver quality medical services in a cost-effective manner.

In any particular market, providers could refuse to contract with us, demand to contract with us, demand higher payments, or take other actions that could result in higher health care costs for us, less desirable products for customers and members or difficulty meeting regulatory or accreditation requirements. In some markets, some providers, particularly hospitals, physician/hospital organizations or multi-specialty physician groups, may have significant market positions and negotiating power. In addition, physician or practice management companies, which aggregate physician practices for administrative efficiency and marketing leverage, may compete directly with us. If these providers refuse to contract with us, use their market position to negotiate favorable contracts or place us at a competitive disadvantage, our ability to market products or to be profitable in those areas could be adversely affected.

In some situations, we have contracts with individual or groups of primary care physicians for an actuarially determined, fixed, per-member-per-month fee under which physicians are paid an amount to provide all required medical services to our members. This type of contract is referred to as a “capitation” contract. The inability of providers to properly manage costs under these capitation arrangements can result in the financial instability of these providers and the termination of their relationship with us. In addition, payment or other disputes between a primary care provider and specialists with whom the primary care provider contracts can result in a disruption in the provision of services to our members or a reduction in the services available to our members. The financial instability or failure of a primary care provider to pay other providers for services rendered could lead those other providers to demand payment from us even though we have made our regular fixed payments to the primary provider. There can be no assurance that providers with whom we contract will properly manage the costs of services, maintain financial solvency or avoid disputes with other providers. Any of these events could have an adverse effect on the provision of services to our members and our operations.

If we fail to manage prescription drug programs successfully, our financial results could suffer.

In general, prescription drug costs have been rapidly rising over the past few years. These increases are due to the introduction of new drugs costing significantly more than existing drugs, direct to consumer advertising by the pharmaceutical industry that creates consumer demand for particular brand-name drugs, and members seeking medications to address lifestyle changes. In order to control prescription drug costs, we have

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implemented multi-tiered copayment benefit designs for prescription drugs, including our four-tiered copayment benefit design, Rx4 and an Rx allowance program structured to account for those drugs that treat more pervasive conditions and are suggested to be more effective by empirical data.

We cannot assure that these efforts will be successful in controlling costs. Failure to control these costs could have a material adverse effect on our financial position, results of operations and cash flows.

Our ability to obtain funds from our subsidiaries is restricted.

Because we operate as a holding company, we are dependent upon dividends and administrative expense reimbursements from our subsidiaries to fund the obligations of Humana Inc., our parent company. These subsidiaries generally are regulated by states’ Departments of Insurance. We are also required by law to maintain specific prescribed minimum amounts of capital in these subsidiaries. The levels of capitalization required depend primarily upon the volume of premium generated. A significant increase in premium volume will require additional capitalization from our parent company. To fund our expanding business opportunities, including the enhanced Medicare business, we anticipate additional required capital ranging from $450 million to $650 million in 2006. In most states, we are required to seek prior approval by these state regulatory authorities before we transfer money or pay dividends from these subsidiaries that exceed specified amounts, or, in some states, any amount. In addition, we normally notify the state Departments of Insurance prior to making payments that do not require approval. In the event that we are unable to provide sufficient capital to fund the obligations of Humana Inc., our operations or financial position may be adversely affected.

Ratings are an important factor in our competitive position.

Claims paying ability, financial strength, and debt ratings by recognized rating organizations are an increasingly important factor in establishing the competitive position of insurance companies. Ratings information is broadly disseminated and generally used throughout the industry. We believe our claims paying ability and financial strength ratings are an important factor in marketing our products to certain of our customers. Our debt ratings impact both the cost and availability of future borrowings. Each of the rating agencies reviews its ratings periodically and there can be no assurance that current ratings will be maintained in the future. Our ratings reflect each rating agency’s opinion of our financial strength, operating performance, and ability to meet our debt obligations or obligations to policyholders, but are not evaluations directed toward the protection of investors in our common stock and should not be relied upon as such. Downgrades in our ratings, should they occur, may adversely affect our business, financial condition and results of operations.

Increased litigation and negative publicity could increase our cost of doing business.

The health benefits industry continues to receive significant negative publicity reflecting the public perception of the industry. This publicity and perception have been accompanied by increased litigation, including some large jury awards, legislative activity, regulation and governmental review of industry practices. These factors may adversely affect our ability to market our products or services, may require us to change our products or services, may increase the regulatory burdens under which we operate and may require us to pay large judgments or fines. Any combination of these factors could further increase our cost of doing business and adversely affect our financial position, results of operations and cash flows.

None.

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Our principal executive office is located in the Humana Building, 500 West Main Street, Louisville, Kentucky 40202. In addition to this property, our other principal operating facilities are located in Louisville, Kentucky, Green Bay, Wisconsin, Tampa Bay, Florida, Cincinnati, Ohio and San Juan, Puerto Rico, all of which are used for customer service, enrollment, and claims processing. Our Louisville and Green Bay facilities also house other corporate functions.

We own or lease these principal operating facilities in addition to other administrative market offices and medical centers. We no longer operate most of these medical centers but, rather, lease them to their provider operators. The following table lists the location of properties we owned or leased, including our principal operating facilities, at December 31, 2005:

Managed Care Industry Purported Class Action Litigation

Since 1999, we have been involved in several purported class action lawsuits that were part of a wave of generally similar actions targeting the health care payer industry and particularly managed care companies. These included a lawsuit against us and originally nine of our competitors that purported to be brought on behalf of physicians who treated our members since January 1, 1990. The plaintiffs asserted that we and other defendants paid providers’ claims incorrectly by paying lesser amounts than they submitted. These cases were consolidated in the United States District Court for the Southern District of Florida (the “Court”), and styled In re Managed Care Litigation.

On October 17, 2005, we and representatives of over 700,000 physicians and several state medical societies reached an agreement (“Settlement Agreement”) to settle the lawsuit by payment of $40 million for the physicians and an amount up to $18 million for the plaintiffs’ attorneys, subject to approval by the Court. The Settlement Agreement recognizes that we have undertaken certain initiatives to facilitate relationships with, and payments to, physicians and provides for additional initiatives over its four-year term. The Court preliminarily approved the Settlement Agreement on October 19, 2005, and set a Settlement Hearing for March 6, 2006.

Three other defendants, Aetna Inc., Cigna Corporation, and The Prudential Insurance Company of America previously entered into settlement agreements that have been approved by the Court. Health Net, Inc. announced a settlement agreement on May 2, 2005, and Wellpoint, Inc. (formerly WellPoint Health Networks, Inc. and Anthem, Inc.) announced a settlement agreement on July 11, 2005.

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In connection with the settlement and other related litigation costs, we recorded pretax administrative expense of $71.9 million ($44.8 million after taxes, or $0.27 per diluted common share) in the third quarter of 2005.

Other Litigation and Proceedings

In July 2000, the Office of the Florida Attorney General initiated an investigation, apparently relating to some of the same matters that are involved in the managed care industry purported class action litigation described above. On September 21, 2001, the Texas Attorney General initiated a similar investigation. No actions have been filed against us by either state.

In addition, our business practices are subject to review by various state insurance and health care regulatory authorities and federal regulatory authorities. There has been increased scrutiny by these regulators of the business practices of managed care companies, including allegations of anticompetitive and unfair business activities, claims payment practices, commission payment practices, and utilization management practices. Some of these reviews have resulted in fines imposed on us and required changes in some of our practices. We continue to be subject to these reviews, which could result in additional fines or other sanctions being imposed on us or additional changes in some of our practices.

We also are involved in other lawsuits that arise in the ordinary course of our business operations, including claims of medical malpractice, bad faith, nonacceptance or termination of providers, improper rate setting, failure to disclose network discounts and various other provider arrangements, as well as challenges to subrogation practices. We also are subject to claims relating to performance of contractual obligations to providers, members, and others, including failure to properly pay claims and challenges to the use of certain software products in processing claims. Pending state and federal legislative activity may increase our exposure for any of these types of claims.

In addition, some courts have issued rulings which make it easier to hold plans liable for medical negligence on the part of network providers on the theory that providers are agents of the plans and that the plans are therefore vicariously liable for the injuries to members by providers.

Personal injury claims and claims for extracontractual damages arising from medical benefit denials are covered by insurance from our wholly owned captive insurance subsidiary and excess carriers, except to the extent that claimants seek punitive damages, which may not be covered by insurance in certain states in which insurance coverage for punitive damages is not permitted. In addition, insurance coverage for all forms of liability has become increasingly costly and coverage for certain forms of liability may become unavailable or prohibitively expensive in the future.

The outcome of current suits or likelihood or outcome of future suits or governmental investigations cannot be accurately predicted with certainty. In addition, the potential for increased liability for medical negligence arising from claims adjudication, along with the increased litigation that has accompanied the negative publicity and public perception of our industry, adds to this uncertainty. Therefore, such legal actions and government audits and investigations could have a material adverse effect on our financial position, results of operations, and cash flows.

Not applicable.

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PART II

Our common stock trades on the New York Stock Exchange under the symbol HUM. The following table shows the range of high and low closing sales prices as reported on the New York Stock Exchange Composite Tape for each quarter in the years ended December 31, 2005 and 2004:

As of January 31, 2006, there were approximately 5,700 holders of record of our common stock.

Our stockholders’ rights plan expired in accordance with its terms in February 2006.

There were no common shares acquired by the Company in open market transactions in 2005. During 2005, we acquired 68,296 shares of our common stock in connection with employee stock plans at an aggregate cost of $2.4 million, or an average of $34.62 per share.

Since February 1993, we have not declared or paid any cash dividends on our common stock. We do not presently intend to pay dividends, and we currently plan to retain our earnings for future operations and growth of our businesses.

The information required by this part of Item 5 is incorporated herein by reference from our Proxy Statement for the Annual Meeting of Stockholders scheduled to be held on April 27, 2006 appearing under the caption “Equity Compensation Plan Information” of such Proxy Statement.

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