Enrollment Periods

When you first sign up for Medicare, you choose between Original Medicare and a Medicare Advantage plan, with or without a separate drug plan. That choice isn't locked in forever — Medicare sets aside specific windows throughout the year where you're allowed to make changes. Here's what each one covers.

Annual Enrollment

Oct 15 – Dec 7

Open to everyone. Switch plans, add or drop drug coverage. Changes start January 1.

Advantage Open Enrollment

Jan 1 – Mar 31

For those already on a Medicare Advantage plan. One change allowed.

Special Enrollment

Triggered by life events

Opens after a move, loss of coverage, or similar qualifying change.

The Fall Annual Enrollment Period

October 15 – December 7

This is the one enrollment window every Medicare member gets each year, no qualifying event required. Whatever changes you make take effect on January 1 of the following year.

During this window, you're free to:

  • Move from Original Medicare into a Medicare Advantage plan
  • Leave a Medicare Advantage plan and return to Original Medicare
  • Switch from one Medicare Advantage plan to a different one
  • Enroll in a Part D prescription drug plan for the first time
  • Switch to a different Part D plan, or drop your drug coverage altogether

Medicare Advantage Open Enrollment Period

January 1 – March 31

Think of this as a second look, but only if you're already enrolled in a Medicare Advantage plan. It's more limited than the fall window — you get to make one change, not several.

During this period, you're allowed to:

  • Switch to a different Medicare Advantage plan
  • Drop Medicare Advantage entirely and return to Original Medicare
  • Add a Part D drug plan, if you're moving back to Original Medicare
  • Drop a Part D drug plan you no longer want
Worth knowing: if you leave Medicare Advantage during this window and hope to pick up a Medicare Supplement (Medigap) policy, acceptance isn't automatic. Outside of your original guaranteed-issue window, carriers are generally allowed to medically underwrite you, meaning they can decline coverage or charge more based on your health.

Special Enrollment Periods

Opens after a qualifying life event

Outside the two scheduled windows above, certain changes in your life can open a Special Enrollment Period, giving you a chance to adjust your coverage without waiting for the next calendar window. Common situations include:

  • Moving to a new address outside your current plan's coverage area
  • Losing other health coverage you had, such as through an employer
  • Becoming eligible for both Medicare and Medicaid

How long you have to act varies by situation, though many Special Enrollment Periods last around two months from the date of the qualifying event. If something in your life has changed recently, it's worth checking sooner rather than later — these windows don't stay open indefinitely.