Medicare Enrollment Periods

Initial Enrollment Period (IEP)

Your IEP is a 7-month window centered on your 65th birthday. It opens 3 months before the month you turn 65, includes your birthday month, and closes 3 months after. Enroll early in this window to avoid gaps in coverage. If you enroll in the last 3 months, your coverage may start up to 3 months late.

Special Enrollment Period (SEP)

If you or your spouse are still working at 65 and have employer-sponsored health insurance through an active employer, you can delay Medicare without penalty. Once that employment or coverage ends, you have an 8-month SEP to enroll in Part B without a late penalty. COBRA and retiree coverage do not qualify as creditable coverage for SEP purposes.

Annual Enrollment Period (AEP)

AEP runs October 15 through December 7 each year. During this window you can switch Medicare Advantage plans, switch from Medicare Advantage to Original Medicare, join or change a Part D drug plan, or switch from Original Medicare to Medicare Advantage. Changes take effect January 1.

Medicare Advantage Open Enrollment Period (OEP)

January 1 through March 31 each year. If you are enrolled in a Medicare Advantage plan, you can switch to a different Advantage plan or return to Original Medicare once during this period. You cannot use OEP to join a Medigap plan without medical underwriting.

Late enrollment penalties

Penalties are permanent and added to your monthly premium for as long as you have Medicare.

• Part B penalty: 10% premium increase for each full 12-month period you were eligible but did not enroll without employer coverage.
• Part D penalty: 1% of the national base beneficiary premium for each month without creditable drug coverage, rounded to the nearest $0.10.
• Part A penalty: 10% premium surcharge for 2 years if you have to buy Part A and delayed enrollment.

Common questions