Millions of Americans on Medicare can switch their drug plan every fall and change their Medicare Advantage plan annually — but changing a Medigap supplement plan is a different story. Outside of a narrow enrollment window or specific life events, insurers in most states can legally turn you away or charge you significantly more based on your health history. A new policy analysis from the Center for American Progress calls this dynamic the 'Medigap trap' and argues it undermines the promise of choice in Medicare.
What Is the Medigap Trap?
Medigap — also called Medicare Supplement Insurance — is private coverage sold alongside Original Medicare (Parts A and B) to help pay costs like deductibles, copayments, and coinsurance. Unlike Medicare Advantage, Medigap works with any doctor or hospital that accepts Medicare, with no networks.
The trap emerges from a quirk in federal law. When you first become eligible for Medicare and enroll in Part B, you have a six-month Medigap Open Enrollment Period during which insurers must sell you any plan they offer at standard rates, regardless of your health. After that window closes, federal law does not require insurers to accept new applicants — and most states follow that federal floor.
In practice, this means a 70-year-old with diabetes or a heart condition who wants to switch from one Medigap plan to another may be denied coverage outright or quoted a premium so high it is effectively unaffordable. The result: many beneficiaries stay in plans that may no longer serve them well, not by choice, but because they have no realistic alternative.
Why This Matters for Real People
The consequences are not abstract. Consider a beneficiary who enrolled in a Medigap plan at 65 that seemed right at the time but now wants a plan with different cost-sharing, or one that has become more affordable. Without guaranteed-issue protections, that person is stuck — unless they qualify for one of a limited set of special enrollment triggers, such as losing employer coverage or moving out of a plan's service area.
According to KFF (formerly the Kaiser Family Foundation), roughly 14 million Medicare beneficiaries are enrolled in Medigap plans. Many of them made their plan choice at 65 with incomplete information about their future health needs. The inability to course-correct without medical underwriting creates a market that rewards healthy enrollees and penalizes those who need coverage most.
How a Few States Already Do It Differently
The Guaranteed-Issue State Models
New York, Massachusetts, and Connecticut have enacted state laws requiring Medigap insurers to accept applicants year-round, regardless of health status. These states demonstrate that guaranteed-issue Medigap is operationally feasible. Insurers participate in these markets, plans remain available, and beneficiaries have genuine flexibility.
Critics of expanding this model nationally sometimes argue it could raise premiums by attracting sicker enrollees. Proponents counter that a larger, more diverse national risk pool — combined with proper regulatory design — could mitigate that concern, and that the current system simply shifts costs and burdens onto vulnerable older adults.
What Policy Reform Could Look Like
The Center for American Progress Proposal
The Center for American Progress analysis proposes giving all Medicare beneficiaries a guaranteed right to purchase or switch Medigap plans at least once per year, similar to how the Affordable Care Act's marketplaces operate. The report argues this would reduce the lock-in effect, increase competition among insurers, and give beneficiaries the kind of real choice that Medicare's design promises but does not always deliver.
Additional proposals in the reform conversation include requiring insurers to use community rating — charging everyone the same rate regardless of age or health — and standardizing plan benefits further so consumers can make apples-to-apples comparisons.
What You Can Do Right Now
Protect Yourself During Your Initial Enrollment Window
Until federal law changes, the single most important action a new Medicare enrollee can take is to choose a Medigap plan carefully during that initial six-month Open Enrollment Period. During this window, you have full guaranteed-issue rights. Insurers cannot deny you, charge you more, or make you wait for coverage because of a pre-existing condition.
Missing this window — or delaying Part B enrollment without a qualifying reason — can permanently limit your options.
Know Your State's Rules
State protections vary significantly. Some states offer additional guaranteed-issue rights beyond the federal minimum, including birthday rules (which allow you to switch to a plan with equal or lesser benefits around your birthday each year) in states like California, Oregon, and Idaho. Check your state's insurance department website or contact your State Health Insurance Assistance Program (SHIP) counselor for free, unbiased guidance.
Understand Qualifying Life Events
Even outside of open enrollment, certain events trigger a guaranteed-issue right under federal law. These include losing Medigap coverage through no fault of your own, leaving a Medicare Advantage plan under specific circumstances, or moving out of a plan's service area. Knowing these triggers can open a window when you need it most.
The Bigger Picture
The Medigap trap is ultimately a story about how insurance market design shapes real-world choices. When the rules favor insurers' ability to screen out risk, the people who most need coverage flexibility — older adults with chronic conditions — are the ones who lose it. The policy debate now underway reflects a broader question: should Medicare's promise of comprehensive, portable coverage extend fully to the supplemental market that millions of beneficiaries depend on?
For now, the answer depends largely on where you live and when you enrolled. Advocates and researchers are pushing for a national answer that works for everyone.