Every fall, a handful of Medicare Advantage insurers decide not to bring a plan back for the following year, and federal law spells out exactly how much warning members are owed before that happens. The rule works on two clocks at once: a rolling 90-day minimum tied to the plan’s actual end date, and a practical calendar deadline that falls in the first days of October for the vast majority of plans, which run on the calendar year. Knowing which deadline applies, and what the mailed notice is legally required to say, determines how much runway is left to compare replacement coverage before Medicare’s enrollment season gets busy.
The Federal 90-Day Rule Behind The October Deadline
The requirement lives in a specific federal regulation, 42 CFR 422.506, which governs how a Medicare Advantage organization exits a contract with the Centers for Medicare & Medicaid Services. The rule runs in two stages. First, an insurer that will not renew has to tell CMS in writing by the first Monday in June of the year the contract ends, a deadline that for any plan leaving the program at the close of 2026 has already come and gone. Second, and separately, the insurer must mail a written notice to every affected enrollee at least 90 calendar days before the plan’s actual end date.
Because nearly every Medicare Advantage contract runs on the calendar year and ends December 31, counting back 90 days lands in the first days of October, which is why insurers and advocacy groups have long described the mailing deadline in shorthand as “by October 1”, even though the regulation itself is written as a countdown rather than a fixed date on the calendar. A termination tied to a mid-year contract exit, though rare, would still follow the same 90-day floor measured from whatever date coverage actually ends, not from October at all.
Free download: How to read the Annual Notice of Change, spot the cost, drug and network changes, and decide whether to keep or switch. Get the free 2027 plan-change checklist.
What A Non-Renewal Letter Must Spell Out
The mailed notice is not a free-form goodbye letter. Under the same regulation, it has to state that the plan is ending and name the exact date, and it must also address what happens next: either a CMS-approved written description of the other Medicare Advantage, Medicare Advantage prescription drug, and standalone Part D plans available in the enrollee’s area, or a round of outbound calls placed using a CMS-approved script. What the notice cannot do is double as a sales pitch. The insurer is barred from using it to steer enrollees toward its own replacement plan or a Medigap policy it happens to sell.
Medicare backs this up with its own paperwork. The CMS Non-Renewal Reminder Notice goes out separately, later in the fall, to enrollees whose plan is leaving the program, repeating that a new plan still has to be chosen for the following year. It functions as a second nudge layered on top of the insurer’s own October mailing, not a substitute for it, and it does not reset or extend the insurer’s 90-day obligation.
The Guaranteed-Issue Window A Non-Renewal Opens
Losing a Medicare Advantage plan to nonrenewal carries one protection that voluntarily switching plans does not: a federal guaranteed-issue right to buy certain Medicare Supplement, or Medigap, policies without medical underwriting or a pre-existing condition waiting period. That right is time-limited. The application has to go in within 63 days after coverage under the old plan ends, and it exists specifically because the termination was the insurer’s decision, not the enrollee’s. Someone who simply shops for a different plan on their own during the enrollment season does not carry that same automatic underwriting protection into a Medigap purchase. Several states extend broader guaranteed-issue protections than the federal floor, so the rights on paper can vary by ZIP code even when the notice itself looks identical nationwide.
Where This Notice Fits Next To The Annual Notice Of Change
It is easy to lump the non-renewal notice in with the Annual Notice of Change, the packet most Medicare Advantage enrollees receive each September describing next year’s premiums, deductibles and drug formulary. The two documents answer entirely different questions. An Annual Notice of Change assumes the plan is coming back and explains what is different about it; a non-renewal notice exists only because the plan is not coming back at all, and it runs on its own October timeline rather than the Annual Notice of Change’s late-September one. An enrollee should never read a change in benefits as proof the plan is ending, or silence as proof it is staying.
The timing is not a coincidence. A non-renewal notice generally lands in the first days of October, just ahead of Medicare’s Open Enrollment period, which runs October 15 through December 7, with any new coverage taking effect January 1 and enrollment requests due by December 7. Enrollees who take no action when their plan ends default back to Original Medicare and may need to actively enroll in a standalone Part D drug plan to keep prescription coverage, since that step does not happen automatically. Letting a gap in drug coverage run past 63 days without Part D or other creditable coverage can trigger a permanent, monthly late-enrollment penalty added to future premiums, which turns a paperwork deadline into a recurring household cost.
The Ninety Days Insurers Count And Enrollees Rarely Do
A federal deadline governs when an insurer has to mail its notice, but it says nothing about how to spend the weeks that notice buys. Comparing a replacement plan’s premiums, drug tiers and doctor network takes real legwork, and it lands on the same calendar as the busiest weeks of Medicare’s enrollment season. A rule about mailing dates does not walk anyone through what to do with the time it creates.
The 2027 Medicare Open Enrollment Decision Kit assembles a cost calculator spreadsheet that compares plans on cost, drugs and doctors alongside a provider call script and the Open Enrollment calendar.
Look up the Open Enrollment calendar in The 2027 Medicare Open Enrollment Decision Kit.
AI-assisted research and drafting; reviewed by an editor.
