People whose Medicare Advantage plan ends on Dec. 31 can buy a Medigap supplement policy with no waiting period for existing health problems, but only inside a 63-day window. Outside it, Medicare’s own Medigap guide says an insurer can refuse to pay for a pre-existing condition for up to six months. The research group KFF counts 4.3 million Medicare beneficiaries whose Medicare Advantage or stand-alone drug plan is terminated at the end of 2026.
A pre-existing condition is a health problem a person has before the date a new insurance policy starts, according to Medicare’s Choosing a Medigap Policy guide. The insurer may decline to cover out-of-pocket costs for that problem for a limited time, which Medicare calls a pre-existing condition waiting period. After six months, the Medigap policy covers the condition.
Anyone in a terminated Medicare Advantage plan who wants a Medigap policy for 2027 has two things to settle: whether the plan’s ending counts as a guaranteed-issue event, and whether the application will land inside the 63 days that follow. A missed window can mean medical underwriting, a waiting period or an outright denial, because the rules below protect only buyers with a qualifying right.
Retirement deadlines, in your inbox: Miss an enrollment or claim deadline and the money can be gone. Join the Retirement Money Brief and we’ll send you our 2027 Medicare Plan-Change Checklist as a welcome gift.
Get the Brief + the plan-change checklist →
We may earn a commission from links on this page.
When can an insurer make a Medigap buyer wait six months?
Medigap insurers face the fewest limits during a buyer’s Medigap Open Enrollment Period. That period lasts six months and, according to Medicare, starts the first month a person has Part B and is 65 or older. It happens once, so a person who joined Medicare Advantage years ago and has stayed in it is almost certainly past it.
After that period, Medicare says insurers can use medical underwriting and “may deny you a policy unless you have a guaranteed issue right.” A buyer who is accepted may pay more, and the insurer may add the pre-existing condition wait. The same guide says the wait does not apply to a buyer with at least six months of continuous prior creditable coverage, as long as no break in that coverage ran longer than 63 days.
Medicare’s buying guidance makes the same point in shorter form. Once the open enrollment period ends, insurers are not required to sell a Medigap policy unless the buyer has guaranteed issue rights.
What does a guaranteed-issue right change when a plan ends?
The Medigap guide lists the situations that create the right. They include a Medicare Advantage plan that leaves Medicare, one that stops providing care in the member’s area, a member who moves out of its service area, and a plan whose network changes significantly. The right can be used only to switch back to Original Medicare.
With it, the guide says “the insurance company must cover all your pre-existing health conditions without a waiting period.” That is the opposite of the six-month wait, and it is the reason the timing matters so much for the people whose plans are ending.
How long is the 63-day window, and where does it fall this year?
A person can apply as early as 60 days before Medicare Advantage coverage ends, and no more than 63 days after it ends. Medigap policies cannot start until the Medicare Advantage coverage has ended. For a plan that ends Dec. 31, 2026, that counts out to roughly Nov. 1 through Mar. 4, 2027.
KFF says terminated Medicare Advantage members qualify for a special enrollment period for Medigap with guaranteed issue rights. It also says people who do nothing will be switched automatically to traditional Medicare, so a person who wants a supplement has to apply to an insurer.
Which plans are ending, and how many people hold them?
KFF’s count, built from federal Medicare data, puts the Medicare Advantage drug plans being terminated at about 3.1 million enrollees, with another 1.2 million in stand-alone drug plans. Stand-alone drug plan members are not in Medicare Advantage, so the Medigap right described here applies to the first group.
By insurer, KFF lists Humana at 530,000 Medicare Advantage drug plan enrollees, UnitedHealth Group at 367,000, CVS Health at 254,000 and Aware Integrated, which sold Blue Cross branded plans in Minnesota, at 249,000. Each of those members gets a notice from the plan, and the date in that notice is the one that starts the clock.
Is a Medigap plan the only way out of a plan that is ending?
Not for everyone. Medicare lists a special enrollment period for people whose plan’s contract is not renewed, running from Dec. 8 to the last day of February. During it, a member can join another Medicare Advantage plan or a drug plan, which keeps the person in Medicare Advantage and leaves Medigap out of the picture.
Which Medigap plans are still open also shapes the choice. The guide says Plans C and F are no longer available to people new to Medicare on or after Jan. 1, 2020. People who became eligible before that date may still buy them, and newer enrollees can look at Plans D and G.
Will the Medigap application reach an insurer before the 63 days run out?
For a person whose plan ends Dec. 31, the stake is a wait of up to six months on an existing health problem if the application comes late or the right is not recognized. Insurers decide on the date and the reason for leaving the plan, and a misread notice can cost the right.
“The 2027 Medicare Open Enrollment Decision Kit” is a 55-page guide that includes the Medigap guaranteed-issue rights when a Medicare Advantage plan leaves or a person returns to Original Medicare, with a call script. Part 4 holds the Medigap and IRMAA checkpoints, and Part 6 holds phone scripts and a call log, so each insurer call is written down with its date.
This article was produced with AI assistance and edited for accuracy against the sources linked above.
David M. Keller is a finance writer based in Columbus, Ohio, covering personal finance and consumer-focused economic topics. He earned his degree in journalism from Ohio University and began his career reporting on local business and economic trends for a regional media outlet. Since then, he has contributed to a variety of online publications, focusing on clear, practical coverage of topics such as cost of living, debt, and everyday financial decision-making.
