74% of MA Enrollees Risk Medigap Denial, KFF Finds

KFF Analysis: 74% of Medicare Advantage Enrollees Could Face Medigap Denial

Nearly three-quarters of Medicare Advantage enrollees, an estimated 20.9 million people as of 2023, have a pre-existing health condition that could lead to a denial if they tried to switch to a Medigap policy outside their one-time trial period, according to a KFF analysis published October 13, 2026. Medigap, also called Medicare Supplement insurance, is private coverage sold alongside Original Medicare that helps pay deductibles, copayments, and coinsurance that Medicare Parts A and B do not cover. KFF identified the 74% figure by reviewing the medical conditions that insurers commonly use to deny Medigap applications and comparing those conditions against the health profiles of Medicare Advantage enrollees nationwide.

The finding centers on a narrow federal protection known as the Medigap trial right. Under federal rules, someone who joins a Medicare Advantage plan when first eligible for Medicare, or who drops a Medigap policy to try Medicare Advantage, gets a one-time 12-month window to switch back to Original Medicare and buy a Medigap policy without medical underwriting. Once that window closes, most states allow Medigap insurers to use medical underwriting, meaning they can deny an application or charge a higher premium based on health history, unless the applicant qualifies for one of a small number of other federally guaranteed-issue situations.

Why Medical Underwriting Can Create a One-Way Door Out of Medicare Advantage

The practical effect, according to KFF's analysis, is that most Medicare Advantage enrollees who want to leave their plan after the trial right expires have limited options unless they live in one of the states that go beyond federal minimum protections. A handful of states, including New York and Connecticut, require insurers to sell Medigap policies to applicants year-round regardless of health status, and some other states offer their own annual or situational guaranteed-issue windows. Outside those states, an enrollee with a condition as common as diabetes, heart disease, or a cancer history can be turned down or quoted a higher premium by a Medigap insurer applying underwriting standards.

KFF's analysis also found that the likelihood of a potential denial rises with age, since older enrollees are more likely to have accumulated one or more of the conditions insurers screen for. That detail matters because Medicare Advantage enrollment has grown substantially over the past decade, and a growing share of that enrolled population is aging into the years when health conditions become more common and the practical path back to Original Medicare narrows. Enrollees who later face a network change, a plan exiting their county, or a reduction in covered benefits may find that switching to Original Medicare and Medigap is no longer a guaranteed option, even if it was available when they first enrolled.

What Medicare Advantage Enrollees Should Check Before Switching

For readers weighing a move between Medicare Advantage and Original Medicare, timing is the deciding factor. If you joined a Medicare Advantage plan when you first became eligible for Medicare, or recently dropped a Medigap policy to try Medicare Advantage, confirm the exact date your 12-month trial right began, since that date determines when your guaranteed-issue window to reverse course closes.

The 2026 Medicare Advantage and Part D Annual Enrollment Period runs October 15 through December 7, giving current enrollees a chance to compare 2027 plan benefits, provider networks, and drug formularies before committing for another year. Anyone considering a switch from Medicare Advantage to Original Medicare should check three things: whether they are still inside a federal trial right or another guaranteed-issue period, whether their state offers Medigap protections beyond the federal minimum, and how any pre-existing conditions might affect underwriting if neither protection applies. A licensed insurance agent or a State Health Insurance Assistance Program (SHIP) counselor can help confirm trial right eligibility and review state-specific Medigap rules before a switch is finalized.

Because this decision can affect out-of-pocket costs and coverage flexibility for years, Medicare Plan Path recommends comparing specific plan documents for your state and consulting a licensed agent rather than assuming any single outcome applies to your situation. You can review the full KFF analysis, including state-by-state and age-group estimates, at kff.org.