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.

Where this term matters

Medicare →/life-events →

Tip

Glossary definitions are educational. Always check your own policy language — insurers can define common terms differently from one another. When in doubt, request a written explanation from your agent.

Related terms

Medicare Part AMedicare Part A is premium-free for most beneficiaries and covers inpatient care, but comes with significant cost-sharing including a per-benefit-period deductible.Medicare Part BMedicare Part B charges a monthly premium — $202.90 in 2026 for most beneficiaries — and covers the outpatient medical services that Part A does not.Medicare Part DMedicare Part D covers prescription drugs and features a $2,100 out-of-pocket cap in 2026, ending the coverage gap that previously left beneficiaries with full costs.Annual Enrollment Period (AEP)The AEP is the primary annual opportunity for Medicare beneficiaries to change their Medicare Advantage or Part D drug plan, with changes taking effect January 1.Medicare Special Enrollment PeriodA Medicare SEP lets you enroll in Medicare without late penalties when you lose qualifying employer coverage or experience other defined life events.Medicare Late Enrollment PenaltyThe Medicare late enrollment penalty increases Part B premiums by 10% per year of delay and Part D premiums by 1% per month without creditable coverage — and these surcharges last for life.

Related guides

Source: Cover Forge USA editorial team|Last verified: May 2026|Methodology
Definitions are educational and may be simplified. Always refer to your policy contract and consult a licensed agent for terms that affect coverage decisions.
CF

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 June 2026

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