Medicare Advantage Enrollment Periods

Initial Enrollment Period (IEP)

The Initial Enrollment Period is a 7-month window around your 65th birthday:

3 months before your birthday month
Your birthday month
3 months after your birthday month

This is your first opportunity to enroll in Medicare Advantage. If you enroll before or during your birthday month, coverage starts the first day of your birthday month. If you enroll in the 3 months after, coverage is delayed by 1–3 months.

Annual Enrollment Period (AEP)

The Annual Enrollment Period runs from October 15 to December 7 each year. During AEP, you can:

Switch from Original Medicare to a Medicare Advantage plan
Switch from one Medicare Advantage plan to another
Switch from Medicare Advantage back to Original Medicare
Join, switch, or drop a standalone Part D plan

Coverage changes made during AEP take effect January 1 of the following year.

Medicare Advantage Open Enrollment Period (OEP)

The Medicare Advantage Open Enrollment Period runs from January 1 to March 31 each year. During OEP, you can:

Switch from one Medicare Advantage plan to another
Switch from Medicare Advantage back to Original Medicare (and join a Part D plan)

You cannot use OEP to switch from Original Medicare to Medicare Advantage. Coverage changes take effect the first day of the month after the plan receives your enrollment request.

Special Enrollment Periods (SEPs)

Special Enrollment Periods allow you to make changes outside of regular enrollment windows when certain qualifying events occur:

Moving - Moving out of your plan's service area or to a new address where different plans are available
Losing coverage - Losing employer or union coverage
Gaining/losing Medicaid - Changes in Medicaid eligibility
Plan termination - Your Medicare Advantage plan leaves Medicare or stops serving your area
5-star enrollment - If a 5-star plan is available in your area, you can switch to it once per year (December 8 – November 30)

Frequently Asked Questions

Can I Enroll in Medicare Advantage at Any Time?

No. You can only enroll during specific enrollment periods (IEP, AEP, OEP, or SEP). Outside of these periods, you generally cannot change your Medicare coverage unless you have a qualifying special enrollment event.

What is the Difference between AEP and OEP?

AEP (Oct 15–Dec 7) allows you to make any Medicare coverage change, including switching from Original Medicare to Medicare Advantage. OEP (Jan 1–Mar 31) only allows you to switch between Medicare Advantage plans or switch back to Original Medicare - you cannot use OEP to join Medicare Advantage for the first time.

What Happens if I Miss All Enrollment Periods?

If you miss your Initial Enrollment Period and don't have a qualifying SEP, you'll need to wait for the Annual Enrollment Period (Oct 15–Dec 7). You may also face late enrollment penalties for Part B and Part D if you delayed enrollment without creditable coverage.