Why switching from Medicare Advantage to Medigap isn't always guaranteed

Every autumn, reminders about Medicare Open Enrollment arrive in mailboxes across the country. It is easy to assume that this period offers a clean slate to reconfigure any part of your coverage, including moving freely between Medicare Advantage and traditional Medicare paired with a Medigap policy.

In reality, Medicare Supplement Insurance—commonly called Medigap—operates on entirely different rules. While you can change Part D prescription plans or switch between Medicare Advantage options every year without answering health questions, buying a Medigap policy later in life is not always an automatic right.

Understanding how this protection works can help you make informed decisions before your coverage options narrow.

The power of your initial six-month window

When you first enroll in Medicare Part B at age 65 or older, federal law grants you a specific, six-month Medigap Open Enrollment Period.

During this six-month stretch, private insurers selling Medigap policies are legally required to offer you what is known as guaranteed issue. They cannot turn you down for coverage, delay the start of your policy, or charge you higher monthly premiums because of chronic health conditions, past surgeries, or ongoing prescription needs.

Once that six-month window closes, that federal right generally expires.

How medical underwriting enters the picture

If you choose a Medicare Advantage plan when you first become eligible, or if you drop a Medigap policy later, you can still apply to buy a Medigap plan in future years. However, in most states, insurers are permitted to use medical underwriting to evaluate your application.

Medical underwriting means the insurance company reviews your health history. They may look at past diagnoses, current medications, recent hospitalizations, and your tobacco use. Based on that review, the company has three options:

• They can accept your application at standard rates.
• They can accept your application but charge a substantially higher premium.
• They can decline your application entirely.

For someone managing conditions like heart disease, diabetes with complications, or an autoimmune illness, passing medical underwriting can be difficult or impossible. Many people only discover this restriction when they attempt to leave a network-based Medicare Advantage plan after a major diagnosis.

The trial-right exception and state protections

Federal rules do provide a narrow safety valve known as a "trial right."

If you joined a Medicare Advantage plan when you first became eligible for Medicare at age 65, you have a 12-month trial period. If you decide within that first year that Medicare Advantage does not fit your needs, you have a guaranteed issue right to leave the plan, return to Original Medicare, and buy certain Medigap policies without underwriting.

A similar 12-month trial right applies if you dropped an existing Medigap policy to try a Medicare Advantage plan for the first time.

In addition, a handful of states—including New York, Connecticut, Massachusetts, and Maine—offer stronger consumer protections than federal law mandates, requiring year-round guaranteed issue or regular annual windows where beneficiaries can switch plans regardless of health status. Other states, such as California and Oregon, have "birthday rules" that allow people who already hold a Medigap policy to switch to an equal or lesser policy around their birthday without underwriting.

How to evaluate your options today

If you are currently evaluating your coverage, keep these practical steps in mind:

1. Check your state rules: Contact your State Health Insurance Assistance Program (SHIP). These counselors provide free, unbiased guidance on whether your state offers protections beyond federal minimums.
2. Look ahead three to five years: When choosing between Medicare Advantage and traditional Medicare with Medigap, consider not just your current health, but how you would want to receive care if you developed a complex illness requiring specialized, out-of-network physicians.
3. Do not cancel existing coverage prematurely: If you decide to apply for a Medigap policy and will be subject to underwriting, never cancel your current Medicare Advantage plan until you have received formal, written approval and an effective date from the new Medigap insurer.