Medicare doesn't let you make most changes whenever you want. Changes happen in set windows, and each window allows certain things and not others. Here are the ones that matter for most people.
October 15 to December 7: the fall Open Enrollment Period
This is the main annual window, sometimes called the Annual Enrollment Period. During these eight weeks you can:
- Switch from Original Medicare to a Medicare Advantage plan, or the other way round
- Switch from one Medicare Advantage plan to another
- Join, switch or drop a Part D drug plan
Whatever you choose takes effect on January 1. If you make more than one change during the window, the last one you make before December 7 is the one that counts.
September comes first. Your plan's Annual Notice of Change should reach you by September 30, so you have a couple of weeks to read it before the window opens. Our guide on how to read it takes about ten minutes.
January 1 to March 31: the Medicare Advantage Open Enrollment Period
This window is only for people already in a Medicare Advantage plan. During it you can make one change:
- Switch to a different Medicare Advantage plan, or
- Leave Medicare Advantage and return to Original Medicare, and join a Part D drug plan at the same time
It isn't a second fall Open Enrollment. If you have Original Medicare, you can't use this window to join a Medicare Advantage plan.
Your Initial Enrollment Period
When you first become eligible at 65, you get a seven-month window: the three months before the month you turn 65, your birthday month, and the three months after. Signing up early in that window generally means coverage starts sooner.
January 1 to March 31: the General Enrollment Period
If you missed your Initial Enrollment Period and don't qualify for a Special Enrollment Period, you can sign up for Part A and Part B in this window. Coverage starts the month after you sign up. Signing up late can mean a late enrollment penalty that lasts as long as you have the coverage.
Special Enrollment Periods
Certain life events open their own window outside the calendar: moving out of your plan's service area, losing coverage from an employer, moving into or out of a nursing home, and others. The rules for each are specific, so check the official details before relying on one.
Two deadlines that carry a lasting cost
- Part D drug coverage. If you go 63 days or more in a row without Part D or other creditable drug coverage after your initial window, a late enrollment penalty can be added to your premium for as long as you have drug coverage.
- Medigap open enrollment. You get a six-month window to buy a supplement policy, starting the month you're 65 or older and enrolled in Part B. Outside it, insurers in most states can use medical underwriting.
| Window | Dates | Who it's for |
|---|---|---|
| Fall Open Enrollment | Oct 15 – Dec 7 | Everyone with Medicare |
| Medicare Advantage Open Enrollment | Jan 1 – Mar 31 | Only people already in Medicare Advantage |
| General Enrollment | Jan 1 – Mar 31 | People who missed initial sign-up for Parts A and B |
| Initial Enrollment | 7 months around your 65th birthday | People newly eligible |
For the official calendar and anything about your own situation, see Medicare.gov, call 1-800-MEDICARE (TTY 1-877-486-2048), or contact your State Health Insurance Assistance Program (SHIP) for free one-on-one counseling.
Free printable
The annual review checklist
Seven things to check before December 7, in the order they appear in your plan's letter. The email version is coming soon.