Most Medicare Advantage enrollees could be denied Medigap coverage if they switch

If you are enrolled in a Medicare Advantage plan and have thought about switching back to traditional Medicare, there is a crucial rule you need to understand before making a move. A new analysis from health policy research group [KFF] reveals that nearly three-quarters of Medicare Advantage enrollees—74 percent—have pre-existing health conditions that could cause private insurers to deny them a Medigap supplemental policy.

While federal law prohibits insurers from denying you coverage when you first qualify for Medicare at age 65, that protection does not last forever. For millions of older adults who joined Medicare Advantage and now face chronic health challenges, returning to traditional Medicare could mean facing unlimited out-of-pocket costs without a supplemental policy to cushion the blow.

The hidden barrier in switching coverage

Every autumn, Medicare open enrollment offers you the chance to reassess your healthcare choices. Many beneficiaries assume that moving between private Medicare Advantage plans and federally administered traditional Medicare is a seamless, two-way street. In reality, switching back comes with a major structural catch [KFF].

Traditional Medicare pays for hospital visits under Part A and doctor visits under Part B, but it leaves significant coverage gaps, including a 20 percent coinsurance on most outpatient care without an annual cap on out-of-pocket expenses. To protect their savings, most traditional Medicare enrollees buy a private Medicare Supplement Insurance policy, widely known as Medigap.

However, outside of your initial six-month enrollment window when you first enroll in Medicare Part B, federal rules do not require Medigap insurers to sell you a plan. According to [KFF], roughly 74 percent of current Medicare Advantage enrollees have medical histories—ranging from heart disease and diabetes to cancer or arthritis—that allow Medigap insurers in most states to subject them to medical underwriting. Underwriters can review your health records, charge you substantially higher premiums, impose waiting periods for coverage, or turn your application down entirely.

Why federal protections fall short

The gap in consumer safeguards stems from how federal laws were originally written. When the Affordable Care Act banned pre-existing condition exclusions and medical underwriting for individual major medical plans, Medigap policies were excluded from those requirements [KFF].

Under federal law, you only receive a "guaranteed issue right" to purchase Medigap without health questions in a few narrow situations: during your first six months after enrolling in Part B at 65 or older, within a one-year trial period if you tried Medicare Advantage for the first time, or if your Medicare Advantage plan terminates coverage in your service area. If you chose Medicare Advantage years ago and now want traditional Medicare because your favorite specialist left the plan's network, federal law gives you no right to buy a Medigap policy [KFF].

Where state laws make an exception

Your options largely depend on where you live. While federal safeguards are narrow, a handful of states have enacted broader consumer protections [KFF].

A small group of states—including Connecticut, Maine, Massachusetts, and New York—require Medigap insurers to offer policies on a guaranteed-issue basis year-round or during regular annual enrollment periods, regardless of your medical history. Several other states have enacted "birthday rules" or specific switching windows that allow current policyholders to change Medigap plans without underwriting, though these protections often apply only to people who already own a Medigap policy rather than those transitioning out of Medicare Advantage.

If you live outside these states, you remain subject to standard underwriting criteria. Even relatively common ailments that are well-controlled by daily medication can trigger a denial or make your monthly premium unaffordable.

What you should weigh this enrollment season

Before you make any changes during Medicare open enrollment, take a careful inventory of your health and finances. If you currently have Medicare Advantage and are considering traditional Medicare, speak directly with a licensed Medigap broker or your State Health Insurance Assistance Program (SHIP) before dropping your existing plan.

Crucially, you should apply for a Medigap policy and receive written approval before submitting paperwork to leave your Medicare Advantage plan [KFF]. Leaving your network plan without a confirmed supplemental policy could leave you exposed to uncapped medical bills, turning what was intended to be an improvement in your care into a serious financial strain.