When a Medicare Advantage plan shuts down or stops serving your area, federal law hands you something valuable with a short fuse: the right to buy a Medigap policy that an insurance company cannot refuse you. The clock on that right runs out 63 days after your old coverage ends. Most people have never heard of it until the moment they need it — and some find out after the window has already closed.
The right that opens when a plan leaves Medicare — and only then
The trigger is specific, and getting it wrong is expensive. This guaranteed-issue right attaches when your Medicare Advantage plan itself goes away: the plan leaves the Medicare program, or it stops serving the area where you live. Your insurer ends the relationship, not you.
It does not attach when a hospital and your insurer have a contract fight. If a hospital system leaves your plan’s network, your plan still exists and your enrollment continues — frustrating, but not a qualifying event under this rule. Anyone who tells you a network dispute unlocks a guaranteed Medigap purchase is misreading the rule, and Medicare.gov’s own decision tool walks through exactly which situations qualify. When the real trigger fires, though, the protection is strong: it is the closest thing to a second chance at Medigap that federal law offers after your original six-month open enrollment period is gone.
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Plans A through L: what an insurer must sell you
With the right in hand, you can buy Medigap Plan A, B, C, D, F, G, K, or L from any insurance company that sells that plan in your state. That covers the most popular choices on the market, including Plan G. Because it is a guaranteed-issue purchase, the insurer cannot lean on the medical underwriting that normally applies when you shop for Medigap late — the health questions that can otherwise mean a denial or a steeper premium for someone with a heart condition, diabetes, or a cancer history.
Paperwork is your friend here. Medicare’s guidance says to keep the letters, notices, emails, and claim denials that show your Medicare Advantage coverage ended, because you may need to submit copies with your Medigap application to prove the right exists. The envelope announcing your plan’s exit is not junk mail — it is evidence.
The application window: 60 days before, 63 days after
The timing rules are exact. You may apply for the Medigap policy starting 60 days before the date your Medicare Advantage coverage ends, and no more than 63 days after it ends. Apply early if you can: the Medigap coverage itself cannot start until your Medicare Advantage coverage actually ends, so an early application means no gap between the two.
Note the anchor, too: the clock runs from the date your coverage ends, not from the date you opened the letter. Miss the 63rd day and the guarantee evaporates. You can still apply for Medigap after that, but you are back in ordinary underwriting territory, where an insurer may decline you or charge more because of your health. For a right this valuable, the difference between day 63 and day 64 is the whole story.
Original Medicare only: the condition that trips people up
There is one condition attached, and it is the one people most often miss: the right exists only if you switch to Original Medicare. Join another Medicare Advantage plan instead, and no Medigap guarantee applies — Medigap works alongside Original Medicare, not alongside Medicare Advantage.
The default takes care of itself if you do nothing. Medicare’s rule is that if you don’t join another Medicare Advantage plan during the yearly Open Enrollment Period, which runs October 15 through December 7, you are automatically enrolled in Original Medicare. Landing there preserves the Medigap right; it also usually means you will want a standalone Part D drug plan, since Original Medicare does not include drug coverage — the federal Medicare Plan Finder compares those alongside everything else.
One nearby protection is worth knowing even though it is a different rule. People who joined a Medicare Advantage plan for the first time and are inside their first 12 months have their own path out: under that trial right, Medicare.gov says someone who had a Medigap policy before joining can buy the old policy back if the same insurer still sells it, and if it is gone, can buy Plan A, B, C, D, F, G, K, or L instead, on the same 60-day-before, 63-day-after clock. It is a separate door out of Medicare Advantage that does not require the plan to be shutting down.
State extensions, and one hard line in federal law
Two final pieces round out the rule. First, the 63 days is the federal floor, not always the ceiling: your rights may last an extra 12 months in certain circumstances, and some states add protections of their own. Your state insurance department (every state has one, and Medicare.gov links directly to the national directory of them) can tell you what applies where you live.
Second, the law draws one line that doubles as a scam detector: it is illegal for anyone to sell you a Medigap policy while you have a Medicare Advantage plan. A legitimate agent will time the Medigap policy to start when your old coverage ends; anyone pushing you to buy while your Medicare Advantage enrollment is still active is breaking the rule, not bending it. The mechanics above aren’t folklore — they sit, in nearly those words, on Medicare.gov’s page on when you can buy a Medigap policy: sixty days before, sixty-three days after, Original Medicare only.
This article was produced with AI assistance and reviewed by a human editor. Figures are linked to their primary sources; where a claim could not be verified from the public record, we say so.
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