Which Medicare enrollment period are you in?

Initial Enrollment Period: your first 7 months

It opens 3 months before the month you turn 65 and closes 3 months after. This is when you sign up for Parts A and B, and when you can first join a Medicare Advantage or Part D plan. If you join a plan before your Medicare starts, the plan starts the same day.

Open Enrollment: October 15 to December 7

This is the big one, and it runs every year. Anyone with Medicare can:

• Switch from Original Medicare to Medicare Advantage, or back
• Join, drop or switch Medicare Advantage plans, with or without drug coverage
• Join, drop or switch a stand-alone Part D plan

Changes take effect January 1, as long as the plan gets your request by December 7. For 2027 coverage, that means December 7, 2026.

Medicare Advantage Open Enrollment: January 1 to March 31

Only for people already in a Medicare Advantage plan. You get one change: switch to a different Advantage plan, or drop Advantage and go back to Original Medicare (and add a Part D plan). The change starts the first of the month after the plan gets your request.

What you can’t do here: move from Original Medicare into Advantage, or switch from one stand-alone drug plan to another.

New to Medicare and joined an Advantage plan? You get the same one-change option during your first 3 months with Parts A and B.

Special Enrollment Periods

Life doesn’t wait for October. Moving out of your plan’s service area, losing employer coverage, moving into or out of a nursing home, or qualifying for Extra Help can all open a Special Enrollment Period. Each one has its own rules and time limit, usually a couple of months from the event.

General Enrollment Period: January 1 to March 31

Missed your Initial Enrollment Period and don’t qualify for a Special Enrollment Period? This is when you can sign up for Part B. Coverage starts the month after you sign up, and you may owe a late penalty. After adding Part B this way, you have 2 months to join an Advantage or drug plan.