Every year, some Medicare Advantage members receive a letter they didn't expect: their plan won't be offered in their county next year. For many, this feels like a setback. What arrives instead is an unusual opportunity—a brief federal window to buy Medigap coverage without having your health history examined.
A 70-year-old in Ohio received this letter in October and chose wisely. She switched to Original Medicare and bought Medigap Plan G under what's called a guaranteed-issue right. The plan covered her with no questions about the atrial fibrillation in her medical record. That single choice protected her from one of Medicare's most expensive traps.
Most people think about switching Medicare plans by comparing monthly premiums. That's incomplete math. The real question is whether you can reverse course later. Once you turn 65 and enroll in Medicare Part B, you get a six-month window to buy any Medigap plan without underwriting. After that window closes, insurance companies in most states can examine your health history, charge higher premiums, or deny you outright. A cardiac diagnosis, recent cancer treatment, or hospitalization can make approval difficult or impossible.
When your Medicare Advantage plan is canceled, you get a second window. This one lasts 123 days total: it opens 60 days before your coverage ends and closes 63 days after it terminates. During this period, you can buy Medigap Plan G guaranteed, without health underwriting. The only catch: Medigap coverage itself cannot begin until your Advantage plan ends.
This protection exists only when an Advantage plan leaves your area, stops operating altogether, or you move out of the plan's service territory. It is not available simply because you changed your mind. And it has a critical condition: it only applies when you return to Original Medicare. If you switch to another Advantage plan instead, this federal guarantee evaporates.
Medigap Plan G covers expenses Original Medicare leaves unpaid. It picks up your hospital deductible, hospital coinsurance for extended stays, and skilled nursing facility costs. After you meet your annual Part B deductible, Plan G covers most remaining cost-sharing. In 2026, a Plan G premium for a 70-year-old typically ranges from $130 to $250 monthly, depending on your location, sex, tobacco status, and carrier.
Another Advantage plan might still cost less each month. The difference is what happens next. If you choose a new Advantage plan and that plan is later canceled, returning to Original Medicare may again require health underwriting. You'll have used your one guaranteed opportunity.
Two mistakes commonly waste this protection. The first is treating the cancellation letter as an invitation to choose another Advantage plan without first pricing the Medigap option. The second is counting from the wrong date. The window does not begin when you receive the letter. It begins 60 days before your coverage ends. If your plan terminates December 31, your application period extends into early March.
When the letter arrives, gather two things. First, compare another Advantage plan against Original Medicare plus Plan G plus standalone Part D drug coverage. Write down the total monthly costs and what each option covers. Second, submit your Medigap application during the protected period and include a copy of the nonrenewal notice. Keep dated proof of eligibility and get written confirmation before the window closes.
Some states offer additional Medigap protections. New York and Connecticut provide especially broad access, while Massachusetts, Maine, and others have separate enrollment rules. Your state health insurance assistance program can tell you what applies where you live. The choice between Advantage and Medigap is yours, but the timing is not—this window stays open only 123 days.