Initial Enrollment Period (IEP)
the 7-month window around your 65th birthday month (3 months before, your birthday month, 3 months after). First chance to enroll in Parts A and B, a Part D plan, or a Medicare Advantage plan. See the turning-65 checklist.
Annual Enrollment Period (AEP) — October 15 – December 7
Anyone with Medicare can join, switch or drop a Medicare Advantage or Part D plan. Changes take effect January 1. You can make more than one change; the last one submitted counts. This is also when plan changes for the coming year are published (the Annual Notice of Change your plan mails in September tells you what's changing).
Medicare Advantage Open Enrollment Period — January 1 – March 31
If you're in a Medicare Advantage plan on January 1, you can make one change: switch to another Advantage plan, or drop to Original Medicare and add a Part D plan. You can't use it to switch from Original Medicare into Advantage, and it doesn't give you a guaranteed right to a Medigap policy.
General Enrollment Period — January 1 – March 31
For people who missed their IEP and don't have a Special Enrollment Period: enroll in Part A and/or Part B, with coverage starting the month after you sign up. Late-enrollment penalties may apply.
Special Enrollment Periods (SEPs)
Life events that open their own window, for example:
- Leaving employer coverage (yours or a spouse's): 8 months to enroll in Part B penalty-free; 2 months to join an Advantage or Part D plan.
- Moving out of your plan's service area, or to an area with new plan options.
- Losing Medicaid or Extra Help, or becoming eligible for either.
- Your plan leaves Medicare or reduces its service area.
- Moving into or out of a nursing facility.
- 5-star plans: you can switch into a plan rated 5 stars by Medicare once a year (December 8 – November 30).
- Federally declared disasters or emergencies, and other exceptional circumstances Medicare recognizes.
Medigap Open Enrollment
Separate from all of the above: the 6 months starting the month you are 65 or older and enrolled in Part B. During this window no company can decline you or charge more for health history. It does not repeat, although guaranteed-issue rights (for example, when an Advantage plan leaves your area or you lose employer coverage) give short windows later.
What's Coming Up
The 2026 Annual Enrollment Period runs October 15 – December 7 for coverage starting January 1, 2027. If you're not sure which window applies to you, tell us your situation and we'll confirm it before anything is submitted.
Common Questions
When is Medicare open enrollment?
The Annual Enrollment Period runs October 15 through December 7 every year, with changes effective January 1. The Medicare Advantage Open Enrollment Period runs January 1 through March 31 for people already in an Advantage plan.
Can I change my Medicare Advantage plan after December 7?
If you're in a Medicare Advantage plan, you can make one change between January 1 and March 31. Outside of that you need a Special Enrollment Period — moving, losing employer coverage, qualifying for Medicaid or Extra Help, and other events.
What is the 5-star Special Enrollment Period?
Once per year, from December 8 to November 30, you can switch into a Medicare Advantage or Part D plan that Medicare has rated 5 stars for the current year, if one is available in your area.
I'm retiring after 65 — how long do I have?
You have 8 months after your employer coverage ends to enroll in Part B without penalty, but only 2 months to join an Advantage or Part D plan and only 63 days of guaranteed-issue rights for a Medigap policy. We recommend starting the process before your last day of work.
