How a Medicare Advantage Exit Letter Starts Three Separate Deadlines

If your Medicare Advantage plan ends on Dec. 31, the deadline that matters most is probably not the one in the headlines. It is Thursday, March 4, 2027: the last day you can apply for a Medigap policy, the private supplemental insurance sold to people in Original Medicare, without health questions. That right exists only if you go back to Original Medicare, and once the window closes it is gone.

The letters that start the clock were due by Friday, Oct. 2; UnitedHealthcare dated its notices that day. UnitedHealthcare is shutting plans that cover about 390,000 people, and Humana is exiting plans that cover about 600,000, Bloomberg reported. Healthcare Dive, in a Friday, Oct. 9, report, went wider: more than 3 million seniors are in a plan that was terminated or left their county.

For anyone holding one of those letters, the news is mixed. You have more time than the "choose by Dec. 7" advice implies, and fewer second chances than you might think, because one letter starts three separate clocks.

The first is open enrollment, Thursday, Oct. 15, through Monday, Dec. 7. Anything you pick then starts Jan. 1. So does a choice made under the special period below, as long as it is made by Dec. 31; after that, any switch leaves a gap.

The second is the one most people don't know about. Under Medicare's special enrollment rules, members of a plan whose contract isn't renewed can switch "between December 8 and the last day in February of the following year." For 2027 that is Tuesday, Dec. 8, through Sunday, Feb. 28, another 83 days.

The third runs on its own track. Medicare.gov's guaranteed-issue rights let you apply for Medigap starting as early as 60 days before your Advantage coverage ends (Medicare.gov also points to the date in your plan's termination notice) and "no more than 63 days after." For a Dec. 31 ending, that means applying by Thursday, March 4, four days after the special period closes; the 60-day rule would open the window on Sunday, Nov. 1.

Date	What it controls
Fri., Oct. 2, 2026	Non-renewal notices due (UnitedHealthcare's are dated Oct. 2); members of continuing plans got their change notice by Sept. 30
Thu., Oct. 15 – Mon., Dec. 7, 2026	Open enrollment: any plan change, effective Jan. 1
Sun., Nov. 1, 2026	Earliest date to apply for Medigap with guaranteed issue under the 60-days-before rule; check the date in your termination notice
Tue., Dec. 8, 2026 – Sun., Feb. 28, 2027	Special enrollment period for members of non-renewed plans; choices made by Dec. 31 start Jan. 1, later ones the first of the next month
Thu., Dec. 31, 2026	Last day of the ending plan
Fri., Jan. 1, 2027	Anyone who chose nothing is in Original Medicare, with no drug plan and no Medigap
Thu., March 4, 2027	Last day to apply for Medigap with guaranteed issue (63 days after Dec. 31); only for people in Original Medicare

Apart from the first row, the dates are Medicare.gov's rules applied to a plan ending Dec. 31. From an Oct. 2 letter, that leaves 66 days to the end of open enrollment and 90 until the plan stops paying.

So what happens if you do nothing? On Jan. 1 you are in Original Medicare. The standard Part B premium ($202.90 in 2026) follows you either way. What you lose is less visible: Original Medicare has no annual out-of-pocket limit, while Advantage in-network caps can reach $9,250 in 2026. And you have no drug coverage.

That gap is where waiting costs. Medicare.gov says coverage generally "starts the first of the month after the plan gets your request." A drug plan chosen by Dec. 31, in open enrollment or the special period, starts Jan. 1. Choose on Jan. 15 and it starts Feb. 1, after 31 days without drug coverage. Choose on Feb. 28, the last day of the special period, and it starts March 1: 59 days without it.

Fifty-nine is just under the 63 days in a row that Medicare.gov says can trigger the late-enrollment penalty, which is "permanently added" to your premium. So the special period alone shouldn't cost you that, assuming no other creditable drug coverage. But two months of paying full price at the pharmacy is a penalty of its own.

Nor is there a later rescue. The January-through-March switching window is open "only if you're already in a Medicare Advantage Plan," Medicare.gov says, so someone who drifted into Original Medicare by default can't use it.

Which envelope you got decides your rights

Check what kind of letter you have. KFF explains that "in many cases, enrollees will be moved into a new plan offered by the same insurer automatically if the contract includes another plan of the same type (i.e., HMO or PPO) in the same county."

Those members got an Annual Notice of Change by Sept. 30, not a non-renewal letter. The difference matters. Medicare.gov ties the special period and the Medigap right to a plan that is leaving Medicare or stops serving your area, not to one swapped for a sibling plan. A member moved automatically can still shop during open enrollment but may not have the later windows. If you aren't sure which letter you hold, 1-800-MEDICARE or a state counselor can tell you.

For a true non-renewal, the Medigap door carries the most lasting weight. You can buy Plans A, B, D or G sold in your state; C and F are open only to people who became eligible for Medicare before Jan. 1, 2020. The policy can't start until your Advantage coverage ends. And, in Medicare.gov's words, "You only have this right if you switch to Original Medicare (rather than join another Medicare Advantage Plan)."

That is the real trade. Another Advantage plan may be cheaper or simpler this winter, and for many people it will be the right call. But it quietly spends a right that a healthy member may never miss and a sicker one may badly want back. Your state insurance department may grant "additional rights under state law," Medicare.gov adds, so it is worth a call.

Where the 'millions' come from

The exits are big in people and modest as shares. UnitedHealthcare's 390,000 is about 5.2% of its 7.565 million Advantage members as of June 30, per investor materials cited by TIKR. Humana's 600,000 is about 8.3% of its roughly 7.2 million Advantage members, per MoneyTalks. Together they make 990,000, nearly all of Bloomberg's "at least one million"; Aetna and Centene are shrinking too, Bloomberg reported, citing Wall Street analysts.

Humana said on its July 29 earnings call that "the majority of the plan exits were in plans with three and a half or lower ratings," and it recaptured more than 40% of members after its 2025 exits. Stephens research, cited by Healthcare Dive, found Centene, CVS, UnitedHealthcare and Elevance making 566 county exits between them, while Devoted Health, Humana and Alignment Healthcare made 384 county additions.

What is new is the trend. Forced disenrollment averaged about 1% from 2018 through 2024, according to a JAMA study by researchers at Johns Hopkins and Georgetown. The rate reached 6.9% for 2025, according to CMS data cited by Yahoo Finance. For 2026 it was about 10% of members in individual HMO and PPO plans, or 2.9 million people, and affected enrollees were nearly twice as likely to live in rural areas.

"Medicare Advantage has grown substantially over the last decade. During that time, enrollees have rarely been forced to disenroll from their plans if they wanted to keep them…what we're seeing now is a substantial and sudden reversal of that pattern."

Mark Meiselbach, assistant professor of health policy and management, Johns Hopkins Bloomberg School of Public Health

Washington's message on Sept. 28 was calmer. CMS's 2027 projections show national plans going from 5,553 to approximately 5,532 and "approximately eight in 10" members able to stay in their plan at the same or a lower premium. "We urge beneficiaries to use Open Enrollment as an opportunity to review their coverage, compare options, and pick the plan that best suits their needs and budget," CMS Administrator Dr. Mehmet Oz said.

Both pictures are true, and CMS's own ratio shows how. If eight in 10 can keep their plan at the same or a lower price, about two in 10 cannot. Insurers project 34 million enrollees for 2027, a 6% decline, which implies about 36.2 million this year. By CMS's own ratio, roughly 7 million people face a plan ending, a forced move or a higher premium. The figure is rough, resting on a rounded ratio and mixing endings with price increases, but it fits with Healthcare Dive's "more than 3 million" in terminated plans. "Stable" describes the program, not the fifth of members living through the change.

Choice is thinning, too. KFF's count of plan options puts the average beneficiary at 28 Advantage plans with drug coverage for 2027, down from 32 this year and 36 at the 2024 peak, though still above 2021's 27.

Is a $12 premium really cheaper?

CMS projects the average monthly Advantage premium falling from $14.37 to $12.00, a 16.5% drop. That is $2.37 a month, or $28.44 a year.

The costs that bite in a bad health year moved the other way. Leerink Partners, cited by Healthcare Dive, found out-of-pocket maximums up 10% on average and Part D deductibles up 30%. Healthcare Dive also notes that CMS's average folds in cheaper special needs plans (for people with Medicaid, chronic conditions or institutional care), so it "underestimates premium changes" for everyone else. Set a 10% rise against a cap that can already reach $9,250, and the premium is the smaller number.

Extras are shrinking as well. Humana reduced or eliminated its Part B giveback, a plan refund of part of the Part B premium, for 62% of its members, Leerink found, a loss worth weighing alongside the yearly Social Security adjustment. When comparing replacements, a plan's prior-authorization and step-therapy rules and its drug list can matter as much as its price.

So can its network, because a renewing plan can lose a hospital without changing its name. Fairview Health sued UnitedHealthcare in federal court in Minnesota this week, alleging the insurer's 2027 directories still list Fairview as in-network although Fairview said in June it would not renew. Fairview says it goes out of network Jan. 1; about 33,000 of its patients are in UnitedHealthcare Advantage plans. A hearing was expected Tuesday, Oct. 13.

"We are asking the court to require accurate information before enrollment begins, when patients still have the opportunity to make an informed choice," said Dr. Jaya Kumar, Fairview's chief medical officer.

Medicare.gov lists "Your plan's network has changed significantly" among the situations that can open a Medigap guaranteed-issue right. Whether it applies to you is a question for a counselor. Either way, call your doctors and hospital rather than trusting a directory.

The help is free. Medicare.gov's Plan Finder compares Original Medicare, drug plans, Advantage plans and Medigap side by side. 1-800-MEDICARE (1-800-633-4227) answers 24 hours a day, seven days a week. And free counseling through a SHIP, your State Health Insurance Assistance Program, comes from counselors who don't earn a commission, MoneyTalks reported.

Bring the letter. The non-renewal notice (UnitedHealthcare's is dated Oct. 2) is the document that proves your plan ended, which is what opens the special period and the Medigap guarantee. It belongs in a drawer, not the recycling bin.