Sixty-three days is the outside limit. That is how long a Medicare Advantage member has after their plan’s coverage ends to apply for a Medigap policy with a guaranteed-issue right, under rules Medicare.gov spells out for members whose Medicare Advantage plan is leaving Medicare, exiting their county, or ending its contract outright. The right forces an insurer to sell any Medigap policy sold in the state without medical underwriting; miss the window and the same insurer can ask health questions and price the policy accordingly. The deadline runs from the date coverage actually stops, not from when a member decides to act.
A 60-day head start, a 63-day hard stop
A Medicare Advantage plan’s coverage can end for several distinct reasons, and Medicare.gov treats each one as its own trigger for the guaranteed-issue right: the plan leaving Medicare altogether, a member moving out of the plan’s service area, the plan no longer covering where the member lives, or the plan failing to follow its own enrollment rules. Any of those four situations opens the same clock, regardless of which one actually applies to a given member.
Medicare.gov’s guidance on when to buy a Medigap policy sets the clock itself: an application can go in as early as 60 days before Medicare Advantage coverage ends and as late as 63 days after it ends. Inside that span, the same guidance says the applicant has the right to buy any Medigap policy sold by an insurance company in the state, regardless of health history. Outside it, that right does not exist.
The Medigap window is not the same clock as the one for choosing a new Medicare Advantage or drug plan. Medicare.gov’s page on Special Enrollment Periods says that when Medicare itself ends a plan’s contract, the Special Enrollment Period to pick a replacement runs from one month before the contract ends to two full months after. When a plan ends its own contract or is not renewed instead, that Special Enrollment Period runs from two months before to only one month after.
Before the 63rd day: The 63-day guaranteed-issue deadline does not pause for a member still confirming whether a prospective doctor or hospital takes a new plan. Look up the provider call script in The 2027 Medicare Open Enrollment Decision Kit.
Why the two clocks can pull in different directions
That difference matters because the two decisions land on a member at the same time but do not run on matching schedules. A member whose plan’s contract is ended by Medicare gets close to two months after coverage stops to settle on a new Medicare Advantage or drug plan, a span that runs nearly as long as the entire 63-day Medigap deadline. A member whose plan instead ends its own contract or leaves the market gets only one month after coverage stops to make that same choice, which leaves considerably more room before the separate Medigap clock runs out.
Which version applies depends on who ended the contract, not on anything the member controls or is likely to know without reading the notice closely. A member who takes the fuller two months allowed after a Medicare-initiated termination to compare Medicare Advantage alternatives can already be within days of the 63-day Medigap cutoff by the time that plan choice is finalized, since neither Medicare.gov page describes an extension for time spent weighing options.
The 60-day head start built into the Medigap rule is the main offset to that risk. Because the window opens 60 days before coverage actually ends, a member who learns early that a plan is leaving Medicare or exiting a county can apply for a Medigap policy before Medicare Advantage coverage stops at all, rather than waiting for the Special Enrollment Period to begin and then working against the separate 63-day deadline afterward.
What a missed window costs
Once the 63rd day passes, Medicare.gov’s guidance shifts from a right to a possibility. The preparing-to-buy page states that outside a guaranteed-issue period, an insurance company “is allowed to deny” a Medigap policy to an applicant who does not meet its medical underwriting requirements. The same policy an insurer must issue automatically inside the window becomes one it can decline, or accept only at a price shaped by the applicant’s health, once the window has closed.
That distinction is the actual stakes behind the 63-day figure. A member who assumes the deadline is approximate, or that it will reset once a new Medicare Advantage or Original Medicare choice is settled, is relying on a rule Medicare.gov does not describe. The guaranteed-issue right is tied to the date coverage ended, not to the date a member finishes comparing new options, and it does not reopen once the count of days runs past 63.
Medicare.gov, the federal government’s official site for the program, is explicit that the guarantee and the underwriting exposure sit on opposite sides of a single, fixed count of days rather than on a judgment call about how reasonable the delay was. For a member whose Medicare Advantage plan is ending, that fixed count, not the separate and sometimes longer Special Enrollment Period for choosing a new plan, is the deadline that decides whether Medigap is available without a health question asked.
The comparison a 63-day clock does not wait for
The 63-day Medigap deadline and the Special Enrollment Period that opens when a Medicare Advantage plan’s contract ends are two separate clocks, and Medicare.gov does not merge them into one timeline for a member who still has to decide whether to pick a new Medicare Advantage plan, return to Original Medicare, or add a Medigap policy before either one closes.
The 2027 Medicare Open Enrollment Decision Kit pairs a cost calculator spreadsheet that compares plans on cost, drugs and doctors with an Open Enrollment calendar, built for weighing a Medicare Advantage alternative against the same window a departing member is already working against.
Compare the cost, drug and doctor tradeoffs of staying on Medicare Advantage against Original Medicare and Medigap with The 2027 Medicare Open Enrollment Decision Kit.
This article was researched and drafted with the assistance of AI and reviewed by The Money Overview editorial team.
