Medicare enrollment periods, explained

Medicare's enrollment windows trip a lot of people up — and signing up late can mean permanent penalties. Here are the periods that matter and when to act.

Initial Enrollment Period (IEP)

Your first window is a 7-month span around your 65th birthday: the 3 months before your birth month, your birth month, and the 3 months after. This is when you first sign up for Parts A and B, and can add a Medicare Advantage (Part C) or Part D drug plan.

Annual Enrollment Period (AEP)

Every year from October 15 to December 7, you can switch between Original Medicare and Medicare Advantage, change Advantage or Part D plans, or join/drop drug coverage. Changes take effect January 1.

Medicare Advantage Open Enrollment

From January 1 to March 31, if you're already in a Medicare Advantage plan you get one chance to switch to another Advantage plan or back to Original Medicare.

General & Special Enrollment Periods

• General Enrollment Period (Jan 1–Mar 31): for those who missed their IEP; coverage starts the month after you enroll.
• Special Enrollment Periods: triggered by life events like losing employer coverage or moving — these let you enroll or change outside the normal windows.

Avoiding penalties

Late enrollment in Part B or Part D can add permanent surcharges to your premiums. If you're approaching 65 or losing employer coverage, talk to a licensed agent early so you enroll in the right window.