Congress put Medicare Part C into effect for two reasons: to give Medicare beneficiaries the same kind of plan choices working-age Americans already had through employer coverage, and to make federal Medicare spending more predictable by shifting financial risk to private insurers paid a fixed amount per enrollee. The Balanced Budget Act of 1997 created the program, originally called Medicare+Choice, by adding a new Part C to Title XVIII of the Social Security Act.1GovInfo. Public Law 105-33 – Balanced Budget Act of 1997
The Budget Problem Behind the 1997 Law
The political backdrop shaped everything about how Part C was designed. In the mid-1990s, projections showed the Medicare Trust Fund heading toward insolvency. A Republican-led Congress and the Clinton White House disagreed on plenty, but both sides saw private-sector competition as part of the solution.
Traditional Medicare pays providers for each service a beneficiary receives. Every office visit, lab test, and scan generates a separate claim, and federal spending in any year depends entirely on how much care people use. That makes budgeting an exercise in educated guessing. Congress wanted a mechanism that would convert that unpredictability into a known cost per person, and paying private plans a fixed monthly amount per enrollee did exactly that.
The Earlier Experiment That Made a Permanent Program Possible
Private health plans had been part of Medicare for over a decade before 1997. The Tax Equity and Fiscal Responsibility Act of 1982 first authorized the federal government to sign risk-based contracts with health maintenance organizations willing to cover Medicare beneficiaries. Under those contracts, the government paid each HMO a fixed monthly amount per enrollee instead of reimbursing individual claims, and the HMO absorbed the financial risk of keeping care costs below that payment.
These arrangements were essentially pilot programs. Participation stayed low through the 1980s and early 1990s because many HMOs found the payment rates too low to justify the risk, and beneficiaries in rural areas rarely had a participating plan available. But the concept worked. Private insurers could deliver Medicare-covered services, and policymakers had a working model to build on when pressure to reform Medicare intensified.
The 1997 law replaced those informal demonstration projects with a permanent statutory structure. It required the Secretary of Health and Human Services to enter into contracts with private organizations before they could offer plans, and it spelled out the plan types allowed, including coordinated care plans, provider-sponsored organizations, and preferred provider organizations.1GovInfo. Public Law 105-33 – Balanced Budget Act of 1997 The act also imposed solvency and organizational requirements on any company that wanted to participate, a recognition that handing federal health benefits to private insurers required serious regulatory guardrails.
Giving Beneficiaries Real Choices
One of the clearest goals behind Part C was ending the one-size-fits-all nature of traditional Medicare. Under the original fee-for-service system, every beneficiary had the same coverage rules, the same cost-sharing structure, and no ability to pick a plan design that matched their personal health needs.
Part C changed that by letting beneficiaries pick from plan types familiar to anyone with employer-sponsored insurance: HMOs with tighter networks and lower out-of-pocket costs, PPOs with broader access for a higher price, and hybrid designs in between.2HHS.gov. What Is Medicare Part C? Every eligible beneficiary gained the right to choose between staying in traditional fee-for-service Medicare or enrolling in a private plan.
The choice argument went beyond network structure. Medicare Advantage plans can offer supplemental benefits that traditional Medicare simply does not cover. In 2026, roughly 99 percent of individual Medicare Advantage plans include vision coverage, 98 percent include dental, and 98 percent include hearing benefits.3KFF. Medicare Advantage 2026 Spotlight: A First Look at Plan Premiums and Benefits Fitness programs, over-the-counter allowances, and acupuncture are also common. None of these appear in traditional Medicare.
Congress has steadily expanded what counts as an allowable supplemental benefit. Starting in 2020, the Bipartisan Budget Act of 2018 allowed plans to offer special supplemental benefits for the chronically ill, covering non-medical needs like meal delivery, pest control, and transportation for enrollees with qualifying chronic conditions.3KFF. Medicare Advantage 2026 Spotlight: A First Look at Plan Premiums and Benefits The philosophy is that addressing social determinants of health, like food insecurity or unsafe living conditions, reduces expensive hospitalizations later.
Part C plans also carry a mandatory annual out-of-pocket maximum, which traditional Medicare lacks entirely. For 2026, CMS set that ceiling at $9,250 for in-network services, though many plans set their own limits well below that. For beneficiaries with serious health conditions, this cap can be the single biggest financial reason to choose a private plan over fee-for-service coverage.
None of this changed the baseline federal coverage. If traditional Medicare covers a service, the Medicare Advantage plan must cover it too.2HHS.gov. What Is Medicare Part C? A plan can add benefits on top, but it cannot strip anything from the baseline. That protection matters, because the entire model depends on beneficiaries trusting that choosing a private plan does not mean giving up guaranteed federal coverage.
Making Federal Spending Predictable
The way CMS pays Part C plans is central to the budgetary reasoning behind the program. Instead of reimbursing each service, CMS pays each plan a fixed monthly amount per enrollee.4Centers for Medicare & Medicaid Services. Capitation and Pre-payment This is called capitation. The payment does not change based on whether the enrollee needs heart surgery or just an annual checkup that month. If care costs exceed the payment, the plan absorbs the loss. If costs come in lower, the plan keeps the difference.
The incentive structure flips fee-for-service on its head. Plans make more money by keeping people healthy and avoiding unnecessary procedures, not by billing for more services. And from a federal budgeting perspective, capitation converts an unpredictable stream of individual claims into a known monthly cost per person.
CMS does not pay every plan the same flat rate. Monthly payments are adjusted using a risk score that accounts for each enrollee’s age, health conditions, and other factors that predict how expensive their care will be.4Centers for Medicare & Medicaid Services. Capitation and Pre-payment A plan enrolling a 68-year-old with diabetes and heart failure receives a substantially higher monthly payment than one enrolling a healthy 66-year-old. Risk adjustment exists to prevent plans from profiting by cherry-picking healthy beneficiaries and avoiding those with expensive chronic conditions. Federal law requires CMS to use a methodology that accounts for variations in health status among enrollees.5Office of the Law Revision Counsel. 42 USC 1395w-23 – Payments to Medicare+Choice Organizations
Whether this actually saves money compared to traditional Medicare is contested. Critics point out that CMS often pays Medicare Advantage plans more per beneficiary than it would have spent on the same person in fee-for-service Medicare. But the predictability alone was a major reason Congress built Part C around the capitation model.
The 2003 Fix That Made the Program Stick
The original Medicare+Choice program struggled during its first several years. Payment rates were a sore point for insurers, and many plans withdrew from rural and suburban markets, leaving some beneficiaries with no private option at all. Congress responded with the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, which reworked the program in two important ways.
The law formally rebranded Medicare+Choice as “Medicare Advantage,” establishing that any reference to the old name in federal law would read as a reference to the new program.6GovInfo. Medicare Prescription Drug, Improvement, and Modernization Act of 2003 More importantly, it increased payment rates to private plans, which made participation more financially attractive and reversed the market withdrawals of the late 1990s.
The 2003 law also created Medicare Part D, the new voluntary prescription drug benefit. For Medicare Advantage organizations offering coordinated care plans, the law required at least one plan option that bundled medical coverage under Parts A and B with prescription drug coverage.7Federal Register. Medicare Program; Medicare Prescription Drug Benefit These integrated plans, known as MA-PD plans, became available starting January 1, 2006, and gave beneficiaries a single plan covering hospital stays, doctor visits, and medications. That integration turned out to be one of the strongest selling points for the program going forward.
Did the Program Meet Its Goals?
The enrollment trajectory suggests the choice half of the argument was persuasive to beneficiaries. In 2011, about 11.7 million people were enrolled, representing 26 percent of eligible Medicare recipients. By February 2025, that number had tripled to 34.4 million, or 55 percent of eligible beneficiaries.8MedPAC. Medicare Advantage – MedPAC Data Book For 2026, enrollment is projected to reach approximately 35.1 million.9KFF. Medicare Advantage Enrollment Grew by About 1 Million People
Growth accelerated sharply after the 2003 law increased payment rates. Between 2011 and 2020, enrollment roughly doubled. It nearly doubled again from 2020 to 2025, fueled in part by the expansion of supplemental benefits. The majority crossover happened in 2023, when Medicare Advantage enrollment passed 50 percent of eligible beneficiaries for the first time.8MedPAC. Medicare Advantage – MedPAC Data Book
Whether the program has delivered on the taxpayer-savings goal is a harder question, and prior authorization denials and narrow networks remain persistent complaints. But measured against the 1997 goals of consumer choice and private-sector participation, Part C has grown well past anything its original architects envisioned.