You are eligible for Medicare at 65 if you are a U.S. citizen or have been a lawful permanent resident for five years. Before 65 you qualify after 24 months of Social Security disability benefits, immediately with ALS, or with end-stage renal disease. Part A is premium-free if you or your spouse paid Medicare taxes for 40 quarters.
Eligibility at 65
Most people become eligible the month they turn 65. You do not have to be retired, you do not have to be collecting Social Security, and your income does not matter for eligibility (it matters only for the IRMAA surcharge). If you already receive Social Security retirement benefits, Medicare Parts A and B start automatically the first day of your birthday month; if not, you enroll yourself through Social Security during your Initial Enrollment Period.
Eligibility before 65
- Disability: after you have received Social Security Disability Insurance (SSDI) for 24 months, Medicare starts automatically in month 25.
- ALS (Lou Gehrig’s disease): Medicare starts the same month SSDI benefits begin, with no waiting period.
- End-stage renal disease: you can enroll if you need regular dialysis or a kidney transplant; coverage usually starts the fourth month of dialysis, or earlier with home dialysis training.
Premium-free Part A: the 40-quarter rule
| Quarters of Medicare-covered work | 2026 Part A premium |
|---|---|
| 40 or more (10 years) | $0 |
| 30 to 39 | $311 per month |
| Fewer than 30 | $565 per month |
You can qualify on a current, former (if the marriage lasted 10 years) or deceased spouse’s work record. Part B always has a premium, $202.90 a month in 2026 for most people.
Still working at 65?
If you or your spouse are actively working and covered by an employer plan with 20 or more employees, you can delay Part B without penalty and enroll later in a Special Enrollment Period that lasts eight months after the job or the coverage ends. Employers with fewer than 20 employees are different: Medicare pays first, so you usually need Part B at 65. COBRA and retiree coverage do not count as active employment, so they do not protect you from the Part B penalty.
Citizenship and residency
You must be a U.S. citizen or a lawful permanent resident who has lived in the United States continuously for at least five years before applying. Legal residents who do not meet the work requirement can buy Part A and Part B at the premiums above.