Medicare Enrollment Periods
Medicare has multiple enrollment windows. Missing them can mean permanent monthly penalties added to your premium. Here's what every window means.
Initial Enrollment Period (IEP)
7-month window around your 65th birthday.
Starts 3 months before the month of your 65th birthday, includes your birthday month, and extends 3 months after. Best time to enroll — no medical underwriting for Medigap, no late penalties. Enroll in Part A, Part B, and optionally Part D or a Medicare Advantage plan.
Annual Open Enrollment Period (AEP)
October 15 – December 7 each year.
Change from Original Medicare to Medicare Advantage or vice versa. Switch between Medicare Advantage plans. Add, drop, or switch Part D drug plans. Changes take effect January 1. This is the busiest — and most aggressive — window for broker sales calls.
Medicare Advantage Open Enrollment (MA-OEP)
January 1 – March 31 each year.
If you're already in Medicare Advantage, you can switch to a different MA plan or return to Original Medicare (and add a Part D plan). You can only make one change during this window.
Special Enrollment Periods (SEPs)
Triggered by qualifying life events.
- • Moved to a new address outside your plan's service area
- • Lost employer or union health coverage
- • Left a Medicare Advantage plan in its first year (trial right)
- • Your plan is discontinued
- • You qualify for Extra Help (Part D subsidy)
- • Dual-eligible for Medicare and Medicaid
Late Enrollment Penalties
- Part B late penalty: 10% added to your Part B premium for every 12 months you could have enrolled but didn't. This penalty is permanent — you pay it every month for the rest of your life on Medicare.
- Part D late penalty: ~1% of the national base premium for every month you delayed signing up for drug coverage after being eligible. Also permanent.
- Exception:If you had "creditable" employer coverage (Part D-equivalent), you can enroll without penalty when that coverage ends.
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