That window is narrower than Annual Enrollment in two ways. It is open only to people already enrolled in a Medicare Advantage plan, and it allows one switch: to a different Medicare Advantage plan, or back to Original Medicare with the option to add a stand-alone drug plan. If you are in Original Medicare on December 8, this window is not available to you.
| Your situation | Window | What you can do |
|---|---|---|
| In a Medicare Advantage plan | Jan 1 – Mar 31 | Switch plans once, or return to Original Medicare |
| In Original Medicare | No general window | Wait for next Annual Enrollment unless you qualify for a Special Enrollment Period |
| Your plan was discontinued | Dec 8 – end of February | Choose a new plan under a Special Enrollment Period |
How it works
Medicare Advantage Open Enrollment is a single-use window. Make a change in January and you cannot make another in March. The change takes effect on the first day of the month after your new plan receives the request, so switching in January means coverage starting February 1.
What changes it
Several situations open a Special Enrollment Period that ignores the calendar entirely: moving out of your plan service area, losing employer coverage, qualifying for Medicaid or Extra Help, or your plan being discontinued. Each has its own length. If any of these apply to you, the December 7 deadline is not the constraint you think it is.
What to do next
If you are unhappy with a Medicare Advantage plan you are already in, note the January 1 date and use the time between now and then to compare properly rather than rushing. If you are in Original Medicare and want to change something, December 7 really is your deadline unless you qualify for a Special Enrollment Period, which is worth checking rather than assuming.
Read the full guide: Annual Enrollment, explained in full
Related questions
Can I switch from Original Medicare to Medicare Advantage in January?
No. Medicare Advantage Open Enrollment is only for people already in a Medicare Advantage plan.
How many changes can I make between January and March?
One. The window allows a single change, and it takes effect the first of the following month.
What if I move to another county?
Moving out of your plan service area opens a Special Enrollment Period, which is separate from these windows.
Sources
- Joining a plan — enrollment periods — Medicare.gov (CMS) · read 2026-10-13
This page explains published rules and figures, with the source for each one. It is not advice about your own situation.