Last fact-check: July 27, 2026 · Primary sources: Medicare.gov and Social Security Administration
Quick answer
Your first Medicare sign-up opportunity is usually a seven-month Initial Enrollment Period: three months before the month you turn 65, your birthday month, and three months after. If you miss it and do not qualify for a Special Enrollment Period, the General Enrollment Period runs January 1 through March 31 and coverage starts the month after you enroll.
Key takeaways
- Sign up for Parts A and B through Social Security.
- Use Medicare.gov for Medicare Advantage and Part D plan enrollment.
- Active employer coverage can create an SEP; COBRA does not extend that eight-month employer window.
Medicare enrollment periods
| Period | When it applies | Typical coverage start |
|---|---|---|
| Initial Enrollment Period (IEP) | Seven months: three before through three after the month you turn 65 | Birthday month if enrolled before it; otherwise generally the next month |
| General Enrollment Period (GEP) | January 1–March 31 each year if no IEP or SEP enrollment | Month after enrollment |
| Employer-coverage SEP | While qualifying current-employment coverage applies and generally eight months after coverage or employment ends, whichever comes first | Generally month after enrollment; limited start-date choices may apply |
| Other SEPs | Specific events such as loss of Medicaid, qualifying emergencies, release from incarceration or misinformation | Depends on the specific SEP |
Important birthday and Part A timing rules
Coverage always starts on the first of a month. If your birthday is on the first, premium-free Part A can start the month before you turn 65. Late premium-free Part A enrollment can be retroactive for up to six months, but not before the month you became eligible—an important consideration for Health Savings Account contributions.
Employer coverage and COBRA
For many people with qualifying coverage based on current employment, the Part B SEP ends eight months after the job or group health plan coverage ends, whichever happens first. COBRA and retiree coverage are not current-employment coverage and do not extend that deadline.
Do not assume every employer plan qualifies. Ask the employer benefits administrator how the coverage coordinates with Medicare and use Medicare’s personalized sign-up checker for the exact situation.
How to sign up
- Use Medicare’s sign-up checker to identify the window and start date.
- Apply for Part A and Part B through Social Security.
- If you delayed Part B because of employment, follow SSA’s Part B-only path and provide the required employer-coverage evidence.
- After Parts A and B, compare Medicare Advantage and drug plans on Medicare.gov if needed.
- Save confirmations and verify the effective dates on the Medicare card and plan notices.
Late-enrollment penalties
A Part B or premium-Part A late penalty may apply when the person missed the allowed period and does not qualify for an SEP. The result is fact-specific; do not describe every missed deadline as an automatic lifelong penalty.
Related guides
- Medicare Parts A, B, C and D
- How the Part B premium is paid
- Original Medicare versus Medicare Advantage
Official sources
- Medicare — Enrollment periods and coverage start dates
- Medicare — Prepare to sign up
- SSA — Sign up for Medicare
Editorial status: This guide has been checked against the cited official sources. Independent subject-matter review has not been completed. Enrollment windows and current procedures were checked against the linked Medicare and SSA pages on July 27, 2026. Individual SEP and penalty decisions require official review. The Guru Gazette is independent and is not affiliated with Medicare or SSA.
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