Medicare
Initial Enrollment Period (IEP)
Your IEP spans three months before, the month of, and three months after your 65th birthday — missing it can result in permanent late enrollment penalties.
Last reviewed: May 2026 · Editorial methodology
Definition
The Initial Enrollment Period (IEP) is the first opportunity for most Americans to enroll in Medicare. It spans seven months: the three months before the month you turn 65, the month of your 65th birthday, and the three months after. Enrolling in Part A and Part B during the first three months of the IEP — before your birthday month — ensures coverage begins on the first of your birthday month. Enrolling during or after your birthday month delays the coverage start date by one to three months. If you do not enroll during your IEP and are not covered by qualifying employer-sponsored health insurance through your own or a spouse's current employment, you face permanent late enrollment penalties: 10% added to the Part B premium for each 12-month period of delay, and a Part D penalty of 1% of the national base beneficiary premium per month without creditable drug coverage. Individuals with active large-group employer coverage (not retiree coverage or COBRA) may delay Medicare enrollment penalty-free while that coverage remains in effect.
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Cover Forge USA Editorial Team
Editorial Lead
This article was researched and written by the Cover Forge USA editorial team against federal sources (NAIC, CMS, FEMA, DOL, SSA, state DOIs) and standard policy forms. Bylines organize content by topic — they do not assert individual licensure. See our editorial-policy for details.
Reviewed 2026-06-14
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