Medicare Enrollment Periods
Knowing when you can enroll in Medicare — and what happens if you miss a window — is critical to avoiding permanent late enrollment penalties.
Medicare Enrollment Period Chart
Initial Enrollment Period (IEP)
7 months around your 65th birthday
Your first opportunity to enroll in Medicare Parts A and B. Begins 3 months before your birthday month and ends 3 months after.
Turning 65 Guide →Special Enrollment Period (SEP)
8 months after losing employer coverage
For people who delayed Medicare because they had employer coverage. Triggered when employer coverage ends.
Working Past 65 Guide →General Enrollment Period (GEP)
January 1 – March 31 annually
For those who missed their IEP and don't qualify for an SEP. Coverage begins July 1. Late penalties may apply.
Late Enrollment Penalties →Annual Enrollment Period (AEP)
October 15 – December 7 annually
Switch between Original Medicare and Medicare Advantage, or change your Part D plan. Changes effective January 1.
Annual Changes Guide →Medigap Open Enrollment Period
6 months starting when you enroll in Part B at 65+
Guaranteed issue rights for any Medigap plan — no medical underwriting. This window only occurs once.
Medigap Open Enrollment →Medicare Advantage OEP
January 1 – March 31 annually
If you're already enrolled in a Medicare Advantage plan, you can switch to another MA plan or return to Original Medicare.
MA Enrollment Periods →Missing Your Enrollment Window Has Permanent Consequences
If you miss your Initial Enrollment Period without a qualifying Special Enrollment Period, you may face permanent late enrollment penalties:
- • Part B penalty: 10% added to your premium for each 12-month period you were eligible but didn't enroll
- • Part D penalty: 1% of the national base beneficiary premium for each month without creditable coverage