Annual Medicare enrollment closes on December 7, but members of a plan that is leaving the program do not run out of time that day. Medicare.gov lists a separate special enrollment period for anyone whose Medicare Advantage plan, drug plan or Cost Plan has a contract with Medicare that is not renewed, and it runs from December 8 through the last day of February. Medicare.gov also states what happens to a member who joins no other Advantage plan before the old one ends: enrollment in Original Medicare.
Inside the decision kit: The 2027 Medicare Open Enrollment Decision Kit includes the Open Enrollment calendar and a provider call script for checking whether a replacement plan’s network still includes current doctors.
What the non-renewal window covers
The rule sits on Medicare.gov’s special enrollment periods page, under the entry for a Medicare Advantage Plan, Medicare drug plan or Medicare Cost Plan whose “contract with Medicare isn’t renewed.” The timing is stated in one line: “Between December 8 and the last day in February of the following year.” The page does not carry a last-updated date, so the window is reported here as the page states it.
The entry lets a member switch to another Medicare Advantage plan, another drug plan or another Cost Plan. The same page states the default for the Advantage-plan entries: members are “enrolled in Original Medicare if you don’t join another Medicare Advantage Plan before your current plan ends.”
Why it starts the day after annual enrollment ends
The window is built to follow the annual calendar. The Centers for Medicare & Medicaid Services puts this year’s Open Enrollment run from October 15, 2026, through December 7, 2026, and its enrollment-periods publication, Product No. 11219, dated March 2026, lists Annual Enrollment as October 15 to December 7, with changes taking effect on January 1.
That booklet places the non-renewal period right after it, using the same December 8 start and end-of-February finish. The order of the two periods is the one the booklet prints: annual enrollment first, then the non-renewal period beginning the next day.
When a switch takes effect
CMS’s publication says changes “will take effect the first day of the month after the plan gets your request.” Applied to the non-renewal window, a request that the new plan receives in December would start January 1, while one received in January would start February 1 and one received in February would start March 1.
Three look-alike windows with different clocks
Medicare.gov lists three entries for a plan contract that ends, and the dates are not the same.
- When Medicare ends a plan’s contract, the chance to switch “starts 1 month before the plan’s contract with Medicare ends, and ends 2 full months after the contract ends.”
- When a plan ends its contract, or the plan and Medicare agree to end it, the chance to switch “starts 2 months before the plan’s contract with Medicare ends, and ends 1 full month after the contract ends.”
- When a contract is not renewed, the window is the fixed December 8 through the last day of February.
The first two move with the contract end date. Only the third is pinned to the calendar.
The January through March window is for people still in a plan
CMS’s publication also describes the Medicare Advantage Open Enrollment Period, which “runs from January 1–March 31” for people already in an Advantage plan, and lets them switch to another Advantage plan or drop the plan and go back to Original Medicare. It is a separate period with separate rules, not an extension of the non-renewal window, and the publication ties it to membership in an Advantage plan.
The distinction matters for a member whose plan ended. The non-renewal period comes first and closes at the end of February, while the January through March period belongs to people who are currently in a plan.
Working out which of three enrollment clocks a plan notice triggers
The difficulty is not the December 8 date, which is plain. It is that Medicare.gov keeps three contract-ending entries with three different timings, and a member has to know which kind of ending applies to the plan being left. The two entries tied to a contract end date open and close around that date, so a member reading them against the calendar year-end will land on different weeks than the fixed December 8 window.
The default adds a second source of pressure. A plan that ends without a replacement hands the member Original Medicare, so choosing a successor before the contract ends keeps the member in the plan type they intended. Whether a replacement plan includes current doctors and drugs is a separate check that the member has to make plan by plan.
The free official route is 1-800-MEDICARE (1-800-633-4227) and the Plan Finder tool at Medicare.gov, which Medicare.gov names for comparing and selecting Advantage and drug plans. Switching plans costs nothing and needs no paid help.
Sorting the Medicare plan-ending windows before the old plan stops
A plan contract that is not renewed opens a window that runs from December 8 to the end of February, next to two contract-end windows with different dates. The practical job left over is matching a plan notice to the right window and then comparing the replacement against the doctors and drugs already in use.
The 2027 Medicare Open Enrollment Decision Kit includes the Open Enrollment calendar, a provider call script and a section on Medigap guaranteed-issue rights when a Medicare Advantage plan leaves or a member returns to Original Medicare, with a call script.
See which Medicare switching window applies when a plan contract is not renewed →
This piece was drafted with AI assistance; the dates were checked against Medicare.gov’s special enrollment periods page, CMS’s enrollment-periods publication and CMS’s 2027 plan announcement.
