Most Medicare Advantage enrollees could face Medigap denials if they switch plans

As the annual Medicare open enrollment window gets underway, millions of older adults are reviewing their health coverage and weighing whether to switch plans. Yet many who consider leaving Medicare Advantage for traditional Medicare may encounter an unexpected and costly hurdle: they can be turned down for supplemental coverage simply because of their health history.

According to a new analysis from KFF, nearly three-quarters—74 percent—of Medicare Advantage enrollees live in states where Medigap insurers can deny coverage or impose medical underwriting if an applicant tries to purchase a policy outside of their initial enrollment window [KFF]. The finding highlights a little-understood structural barrier that leaves many beneficiaries feeling effectively locked into their private plans.

The hidden barrier in fall open enrollment

Medicare open enrollment runs every year from October 15 through December 7, giving beneficiaries an opportunity to change their prescription drug coverage, choose a new Medicare Advantage plan, or return to traditional fee-for-service Medicare [KFF]. Advertisements routinely emphasize this flexibility, creating the impression that switching between options is seamless.

Traditional Medicare does not limit patients to specific provider networks, nor does it require prior authorization for most specialist visits or procedures. However, traditional Medicare also lacks an annual out-of-pocket maximum, leaving patients exposed to 20 percent coinsurance costs for physician services, outpatient procedures, and medical equipment. To protect against catastrophic out-of-pocket expenses, most people who rely on traditional Medicare purchase a private Medicare Supplement Insurance policy, widely known as Medigap [KFF].

What many enrollees do not realize until they try to switch is that Medigap does not follow the same consumer protections that govern Medicare Advantage or standard Affordable Care Act plans.

Why switching back is harder than it looks

Under federal law, insurers are required to issue a Medigap policy at standard rates only during a beneficiary's six-month Medigap open enrollment period, which begins the month they turn 65 and enroll in Medicare Part B [KFF]. During that single six-month window, insurers cannot reject applicants, deny coverage for pre-existing medical conditions, or charge higher premiums based on health history.

Once that initial six-month period ends, federal protections largely vanish. If you enrolled in a Medicare Advantage plan when you turned 65 and decide years later—perhaps after receiving a serious diagnosis—to return to traditional Medicare, Medigap insurers in most states can review your complete medical records [KFF]. Underwriters can legally charge significantly higher premiums, exclude coverage for existing medical conditions for a set waiting period, or reject the application entirely [KFF].

Because common chronic conditions such as heart disease, diabetes, cancer, arthritis, and hypertension frequently prompt denials, the very people who most need supplemental coverage to manage heavy medical bills are the ones most likely to be turned away [KFF].

State protections remain an uneven patchwork

Whether an enrollee can obtain a Medigap policy without underwriting depends almost entirely on where they live. Federal rules establish a baseline, but individual states retain the authority to create stronger consumer protections [KFF].

Only a small handful of states—including New York, Connecticut, Massachusetts, and Maine—require Medigap insurers to offer policies on a guaranteed-issue basis year-round or during designated annual periods, regardless of an applicant's age or health status [KFF]. A few other states offer "birthday rules" or limited trial periods that let beneficiaries switch under specific conditions. In the majority of states, however, no such protections exist, leaving 74 percent of Medicare Advantage enrollees subject to medical underwriting if they attempt to change courses [KFF].

Practical steps before you change your plan

If you currently have a Medicare Advantage plan and are considering switching back to traditional Medicare during open enrollment, health advocates recommend several essential precautions:

• Apply for Medigap before dropping your current plan: Never drop your existing Medicare Advantage coverage until you have an approved, written Medigap policy with a confirmed effective date in hand.
• Check your state's rules: Contact your State Health Insurance Assistance Program (SHIP) to learn whether your state offers guaranteed-issue rights, special enrollment periods, or medical underwriting exemptions [KFF].
• Weigh out-of-pocket exposure honestly: If a Medigap policy is unaffordable or unavailable due to your medical history, evaluate whether you can absorb traditional Medicare's uncapped 20 percent coinsurance before making any changes.