Medicare Advantage — the private insurance alternative to Original Medicare — now covers more than half of all Medicare beneficiaries, enrolling roughly 33 million Americans as of 2025. But a growing body of federal investigations, government audits, and independent research suggests that the insurers running these plans may have collected tens of billions of dollars in payments they were never entitled to. Understanding how this happened, and what it means for your coverage and your tax dollars, is essential for any Medicare beneficiary deciding between Original Medicare and a Medicare Advantage plan.
The payment system at the heart of this controversy is called risk adjustment. The federal government pays Medicare Advantage insurers a fixed monthly amount per enrollee, and that amount is adjusted upward when a beneficiary has more serious health conditions. The logic is sound: a plan covering someone with diabetes, heart failure, and chronic kidney disease should receive more funding than one covering a healthy 66-year-old. Insurers submit diagnosis codes to the Centers for Medicare & Medicaid Services (CMS), and those codes determine how much each plan gets paid. The problem, according to federal investigators and the Department of Justice, is that some of the largest insurers in the country have allegedly manipulated this system — adding diagnosis codes for conditions that were never actually treated, conducting chart reviews designed specifically to find billable diagnoses rather than improve patient care, and in some cases submitting codes for conditions that patients didn't have at all.
The financial scale is staggering. The Medicare Payment Advisory Commission (MedPAC), which advises Congress on Medicare spending, has estimated that Medicare Advantage plans are overpaid by roughly $83 billion over a five-year period compared to what the same beneficiaries would have cost under Original Medicare. The HHS Office of Inspector General has repeatedly flagged specific insurers for submitting unsupported diagnosis codes. In 2023, CMS attempted to recover approximately $4.7 billion in overpayments through a risk adjustment data validation audit process — though that effort faced legal challenges from the insurance industry. The Department of Justice has pursued False Claims Act cases against several major insurers, with some resulting in nine-figure settlements.
For beneficiaries, the immediate question is: does this affect my care? The honest answer is that it can, in indirect but meaningful ways. When insurers collect excess payments, those dollars are not automatically reinvested into better benefits for enrollees. Instead, they flow to shareholder returns, executive compensation, and administrative costs. At the same time, the extra benefits that Medicare Advantage plans advertise — dental, vision, hearing, gym memberships, and over-the-counter allowances — are partly funded by the payment premium these plans receive over Original Medicare costs. If CMS tightens payment rules in response to overpayment findings, some of those supplemental benefits may shrink or disappear in future plan years. In 2024 and 2025, many Medicare Advantage plans already reduced their extra benefits compared to prior years, a trend analysts linked in part to CMS adjustments to the risk adjustment model.
There is also a coverage stability concern. When CMS pursues overpayment recovery or tightens audit rules, some insurers respond by exiting markets where their margins are thinner. Beneficiaries in rural areas and smaller markets are most vulnerable to plan exits, which can force mid-year or year-end disruptions. If your Medicare Advantage plan exits your county, you typically receive a Special Enrollment Period (SEP) allowing you to switch to another Medicare Advantage plan or return to Original Medicare — but your access to specific doctors and hospitals may change, and if you want to add a Medigap supplement after returning to Original Medicare, you may face medical underwriting in most states unless you qualify for a guaranteed issue right.
This brings up one of the most important structural differences between Medicare Advantage and Original Medicare that the overpayment debate highlights. Under Original Medicare (Parts A and B), the government pays providers directly based on a fee schedule. There is no intermediary insurer collecting a risk-adjusted capitation payment. Fraud and billing abuse exist in Original Medicare too, but the payment architecture is fundamentally different. When you are enrolled in Original Medicare, you can see any doctor or hospital that accepts Medicare nationwide, without network restrictions. You pay a standard Part B premium — $185.00 per month in 2025 — plus deductibles and 20% coinsurance, which most beneficiaries cover with a Medigap supplemental policy. Medigap plans are standardized by letter (Plan G and Plan N are the most popular for new enrollees), and their premiums vary by insurer and location but not by your health status once you have guaranteed issue rights.
If you are currently in a Medicare Advantage plan and are concerned about what ongoing payment investigations and potential CMS reforms might mean for your benefits, the Annual Enrollment Period running October 15 through December 7 each year is your primary window to make changes. During AEP, you can switch from Medicare Advantage back to Original Medicare, switch between Medicare Advantage plans, or add or change a Part D drug plan. Changes take effect January 1. There is also the Medicare Advantage Open Enrollment Period from January 1 through March 31, during which you can make one switch — either to a different Medicare Advantage plan or back to Original Medicare — but you cannot use this window to enroll in a Medigap plan with guaranteed issue rights in most states.
If you are considering switching back to Original Medicare after a period in Medicare Advantage, the Medigap timing issue is critical. In most states, insurers can use medical underwriting to deny you a Medigap policy or charge you higher premiums based on pre-existing conditions if you are outside a guaranteed issue window. However, thirteen states have enacted birthday rules or continuous open enrollment protections that give you additional flexibility. In California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon, you have a 30-day window around your birthday each year to switch Medigap plans without medical underwriting. New York and Maine go further, requiring guaranteed issue for Medigap year-round. If you live in one of these states, you have meaningfully more flexibility to move between coverage types.
The broader policy implication of the overpayment investigations is that CMS is under increasing pressure from Congress, the HHS Inspector General, and independent watchdogs to reform how it pays Medicare Advantage plans. Proposed and implemented changes include stricter risk adjustment data validation audits, tighter rules on what diagnosis codes can be submitted from chart reviews alone (without a clinical encounter), and enhanced oversight of third-party vendors that insurers hire specifically to mine medical records for billable diagnoses. These reforms, if sustained, will likely compress insurer margins in Medicare Advantage over the next several years. Beneficiaries should watch their Annual Notice of Change — mailed by October 1 each year — carefully, as this document details any changes to premiums, cost-sharing, formularies, and supplemental benefits for the coming plan year. A plan that looks attractive today may look very different in 2026 or 2027 as the payment environment shifts.
To make the most informed decision for your own situation, use the Medicare Plan Finder tool at Medicare.gov to compare your current plan's costs and coverage against alternatives during each enrollment period. If you want independent guidance, your State Health Insurance Assistance Program (SHIP) offers free, unbiased counseling from trained volunteers — find your local SHIP through the SHIP National Technical Assistance Center at shiphelp.org. These counselors can walk you through the actual cost comparison between Original Medicare plus Medigap plus Part D versus a Medicare Advantage plan in your specific county, using your specific medications and preferred providers. Given the ongoing uncertainty around Medicare Advantage payment policy, having that comparison in hand before each AEP is more valuable than ever.