Medicare Advantage Plan Ending Dec 31? Your Medigap Window

Walt is 69, lives in a small town in rural Ohio, and has paid a $0 premium for his Medicare Advantage plan since he turned 65 in 2022. Last week a letter dated September 30, 2026 told him the plan won't exist after December 31. His first reaction was annoyance. His second was worry, because he had a stent put in two years ago and assumed that ruled out ever going back to a Medigap policy. (Walt is a composite, but his mailbox isn't unusual this year.)

If you got a Medicare Advantage non-renewal letter this fall, I want you to read it as more than bad news. It's also the one time in years when an insurer has to sell you a Medigap policy without asking a single health question. That window has hard dates on it, and it's easy to let them slide by while you're busy being irritated at the insurer.

Why so many people are getting this letter

For years, getting dropped by your Advantage plan was rare. A study by Johns Hopkins researchers published in JAMA on February 18, 2026 found that forced disenrollment averaged just over 1% a year from 2018 through 2024. Then it jumped to 6.9% in 2025 and about 10% in 2026, or roughly 2.9 million people who had to find a new plan.

The spread is lopsided. Twelve states saw rates above 20%, rural areas were hit harder, and in Vermont about 92% of Advantage enrollees lost their plan for 2026.

The 2027 round is already here. Plans had to mail non-renewal notices by October 2, 2026. Humana alone is sending them to about 600,000 members, according to Healthcare Finance News, and most of the discontinued plans carry 3.5 stars or lower for 2027. Humana has said it wants its Advantage profit margins back to at least 3% by 2028, and cutting weaker plans is part of getting there. The people in those plans are left to sort it out.

The four dates on your calendar now

There are a lot of windows here, and they overlap in confusing ways. If your plan ends December 31, 2026, these are the ones that matter.

October 15 to December 7, 2026

Regular open enrollment runs through these weeks. Anyone can pick a new Advantage plan or a Part D drug plan, and coverage starts January 1.

November 1, 2026

Starting around this date, you can apply for a Medigap policy under your guaranteed-issue right. Medicare's 2026 guide, "Choosing a Medigap Policy," says you can apply 60 days before your Advantage coverage ends or by the date in your termination notice. The policy can't start until the old plan stops, so applying early just means it's ready to go on January 1.

December 8, 2026 to February 28, 2027

People whose plans aren't renewing get a special enrollment period here. Medicare.gov says you can switch to another Advantage plan or drug plan during this stretch.

March 4, 2027

Your Medigap guaranteed-issue right runs out on this date. Medicare's guide gives you "no more than 63 days after your Medicare Advantage Plan coverage ends," and 63 days after December 31 lands on March 4.

I'd circle December 7 in red, though. Everything after it still works, but it gets messier, as you'll see below.

What "guaranteed issue" buys you

In most states, if you try to switch from Advantage back to Original Medicare plus a Medigap policy, the Medigap insurer gets to look at your health history. It can charge you more or turn you down. That's why so many people feel stuck in Advantage once they've had a heart attack, a cancer diagnosis or a stent like Walt's.

A plan exit flips that rule off for a while. During your guaranteed-issue window, an insurer selling in your state can't price you up or refuse you for health reasons. Medicare's guaranteed-issue table lists Plans A, B, C, D, F and G, with a footnote: if you're new to Medicare on or after January 1, 2020, you get D or G in place of C or F. Walt joined in 2022, so Plan G is on his menu. If you became eligible before 2020, ask a counselor exactly which plans your right covers, because the footnote is murky and some states add protections of their own. Plan N, which a lot of people like because it's cheaper, isn't on that list, so if you want N you're back to answering health questions.

The catch is that this right applies when you go back to Original Medicare. If you simply pick another Advantage plan, you're making the usual choice, and leaving that plan later means underwriting again in most states. We wrote about that trap in detail in our piece on why Medicare Advantage is a one-way door.

Medigap or another Advantage plan? Run your numbers

I won't pretend Medigap is the right answer for everyone. It costs real money every month.

KFF's analysis found the average Medigap premium across all policyholders was $217 a month in 2023, or $2,604 a year. Plan G, the most popular plan with 39% of policyholders, averaged $164 a month that year, about $1,968 a year, with a typical range of $140 to $236 depending on where you live. On top of that you'd need a standalone Part D drug plan and you'd keep paying your Part B premium. Your quotes will depend on your age, state and the insurer, so treat those as ballpark figures.

What you get for that money is predictability. With Plan G, once you've paid the Part B deductible, Original Medicare and the policy cover nearly everything else, and you can see any doctor in the country who takes Medicare without referrals or prior authorization.

I'd sort people into three rough groups.

If you have a chronic condition, see specialists regularly, or live somewhere with thin Advantage networks (a lot of rural counties), this letter is your best shot at Medigap without underwriting. It might not come around again. For Walt, paying around $164 a month for Plan G to stop worrying about networks and out-of-pocket maximums seems like a fair trade, and he can't count on being offered it later at any price.

If you're healthy, your budget is tight, and another Advantage plan in your area covers your doctors and drugs, staying in Advantage is a reasonable call. Just make it knowing you're probably giving up your free pass back to Medigap.

If you're on a tight income, look into Medicare Savings Programs and Extra Help before you decide. Those can change the math a lot.

What happens if you do nothing

This is the part that catches people. If your plan ends and you don't choose anything, you don't lose Medicare. According to Medicare Interactive, run by the Medicare Rights Center, you're automatically put in Original Medicare on January 1 so you still have hospital and doctor coverage.

You won't automatically get a new Part D drug plan, though, unless you get Extra Help (people with Extra Help are placed in a benchmark drug plan). For everyone else, that means a pharmacy counter on January 2 with no drug coverage.

Timing makes it worse. Changes you make by December 31 start January 1. Changes in January start February 1, and changes in February start March 1. So if Walt waits until mid-January to pick a drug plan, he pays full price for whatever he fills in January. You can still use the special enrollment period through February 28, but every month you wait is a month you might be paying retail for prescriptions.

And you'd have no Medigap either, so you'd owe Original Medicare's 20% coinsurance on doctor visits with no cap until you buy a policy.

Bottom Line

If a non-renewal letter showed up in your mailbox, here's what to do this week:

1. Find the letter and write down the exact date your coverage ends. For most people it's December 31, 2026, which puts your Medigap guaranteed-issue deadline at March 4, 2027.
2. Call your State Health Insurance Assistance Program (find yours at shiphelp.org). The counseling is free and they don't sell anything. Ask them to compare a Medigap Plan G plus Part D setup against the Advantage plans still offered in your county.
3. Get two or three Medigap quotes and mention that you have guaranteed-issue rights because your plan is leaving. Apply in November so the policy starts January 1.
4. Pick a Part D plan (or a new Advantage plan with drug coverage) on Medicare's Plan Finder by December 7. You have until February 28, but choosing early is how you avoid a January with no drug coverage.

The letter feels like a loss, and in a sense it is. But for a lot of people with a health history, it's the only door back to Medigap they'll get, and it closes March 4.