Enrollment
Initial Enrollment Period (IEP)
Quick answer
The Initial Enrollment Period (IEP) is your first chance to enroll in Medicare. It's the 7-month window that starts 3 months before your 65th birthday month and ends 3 months after.
Plain-English definition
Sign up during the first 3 months and coverage begins the month you turn 65. Sign up later in the window and coverage starts the month after you enroll.
Why it matters
Missing IEP without qualifying employer coverage can trigger the Late Enrollment Penalty for Part B and Part D.
A simple example
You turn 65 in June. Your IEP is March 1 – September 30.
Common mistakes & misconceptions
Related terms
General Enrollment Period (GEP)
The General Enrollment Period runs January 1 – March 31 for people who missed IEP and don't qualify for a SEP. Coverage starts the month after you enroll.
Special Enrollment Period (SEP)
A Special Enrollment Period (SEP) is a window outside the standard windows when you can join, switch, or drop a plan. SEPs are triggered by qualifying life events like moving, losing employer coverage, or becoming eligible for Medicaid.
Late Enrollment Penalty
The Late Enrollment Penalty (LEP) is a permanent surcharge added to your Part B or Part D premium if you don't enroll when first eligible and don't have other creditable coverage.
Frequently asked questions
When does coverage start?+
Depends on which month within IEP you enroll.
Sources & references
📚 Where this information comes from
- Medicare.gov — official U.S. government site for people with Medicare ↗Primary source for benefits, enrollment periods, and plan comparison.
- CMS.gov — Centers for Medicare & Medicaid Services ↗Federal rulemaking, program updates, and official guidance.
- Social Security Administration — Medicare enrollment & premiums ↗Enrollment, premium withholding, and IRMAA determinations.
When you're ready, compare plans on your own terms
See Medicare Advantage plans from the insurance companies we represent, or walk the course with a licensed agent whenever you'd like a second set of eyes.
We help compare Medicare Advantage plans from the insurance companies we represent, and we don't offer every plan available in your area.
Medicare Caddies is an independent insurance agency. We are not affiliated with, endorsed by, or connected to the U.S. government, the federal Medicare program, or the Centers for Medicare & Medicaid Services (CMS). We help compare Medicare Advantage plans from the insurance companies we represent, and we don't offer every plan available in your area.