Medicare Enrollment Periods: When Can You Sign Up?

Your Initial Enrollment Period is a 7-month window: it begins three months before the month you turn 65, includes your birthday month, and runs three months after.

This is when most people first sign up for Parts A and B and choose any additional coverage. Enrolling early in the window helps your coverage start as soon as possible.

The Annual Enrollment Period runs from October 15 through December 7 every year, with changes generally taking effect January 1.

During AEP you can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, and join, switch, or drop a Part D drug plan. It's a smart time to review your plan, since costs, networks, and drug formularies can change yearly.

If you're already in a Medicare Advantage plan, the Medicare Advantage Open Enrollment Period runs January 1 through March 31.

During this window you can switch to a different Medicare Advantage plan or drop your plan and return to Original Medicare (and join a standalone Part D plan). It gives you one chance each year to correct a plan that isn't working for you.

A Special Enrollment Period lets you make changes outside the usual windows after certain life events — for example, losing employer coverage, moving out of your plan's service area, or other qualifying situations.

SEP rules can be detailed and the timelines matter, so it's worth confirming whether one applies to you before you act.

Missing your window can mean a gap in coverage and, in some cases, a lifelong late-enrollment penalty added to your Part B or Part D premium.

If you're still working past 65 with employer coverage, different rules may let you delay without a penalty. We help you confirm your timing so you can avoid an avoidable mistake.