A new KFF analysis finds that nearly three-quarters of Medicare Advantage enrollees (74%, or 20.9 million people in 2023) had a pre-existing medical condition that could lead private insurers to refuse to sell them a Medigap policy or charge them more if they were to try to purchase one.
Such a scenario typically would arise when a beneficiary attempts to buy Medigap coverage as part of a switch from Medicare Advantage to traditional Medicare. Medical conditions that could trigger a Medigap denial include relatively common conditions among Medicare Advantage enrollees such as peripheral vascular disease, chronic kidney disease, coronary artery disease, and diabetes with related complications, based on a KFF review of Medigap applications, which list conditions subject to medical underwriting, and analysis of Medicare Advantage encounter data.
Federal law prohibits insurers from denying a Medigap policy or charging higher premiums based on medical history in the six months after people 65 and older first enroll in Medicare Part B, and in limited special circumstances thereafter. (Some states also provide additional enrollment rights.) Outside of these situations, Medicare Advantage enrollees with pre-existing health conditions may face higher costs or may find it impossible to buy a Medigap policy if they later switch to traditional Medicare.
Medigap is the most common source of supplemental coverage for people in traditional Medicare. It helps beneficiaries pay out-of-pocket costs and limits their exposure to catastrophic medical expenses. In 2024, 12.9 million beneficiaries, or just under half (46%) of people enrolled in traditional Medicare, had a Medigap policy.
A second KFF analysis provides an updated look at key facts about Medigap, including the characteristics of Medicare beneficiaries with a policy, variation in enrollment by state, and premiums, including trends over time. While premiums vary by state and by policy type, the average monthly premium among current Medigap policyholders was $244 in 2025 -- or $2,926 for a full year of coverage.
Also available from KFF is an updated analysis of federal and state rules related to guaranteed issue requirements for Medigap policies and how they affect beneficiaries’ access to Medigap, including the implications for Medicare beneficiaries under age 65 with long-term disabilities.
