Who Qualifies for Medicare — and When

Federal law makes four groups eligible for Medicare: people 65 and older, people under 65 who have received Social Security Disability Insurance (SSDI) for 24 months, people of any age with End-Stage Renal Disease (ESRD), and people diagnosed with Amyotrophic Lateral Sclerosis (ALS).

Turning 65

You are eligible on the first day of the month you turn 65 (or the prior month if your birthday is on the first). U.S. citizens and lawful permanent residents who have lived in the country for at least 5 continuous years qualify.

Premium-free Part A

You get Part A at no premium if you (or a spouse) have at least 40 quarters of Medicare-covered employment — roughly 10 years of paying Medicare payroll taxes. Fewer than 40 quarters means you can still buy Part A: $285/month with 30–39 quarters, $518/month with fewer, in 2025.

Disability (SSDI)

People under 65 receiving SSDI qualify for Medicare after 24 months of benefits (the "24-month rule"), effective the 25th month. There is no waiting period for people with ALS: Medicare begins the month SSDI payments begin.

End-Stage Renal Disease

People of any age with permanent kidney failure requiring dialysis or transplant qualify for Medicare. Coverage generally begins the fourth month of dialysis (sooner in specific circumstances) and continues 36 months after a successful transplant.

Automatic vs. self-enrollment

• Already receiving Social Security retirement benefits at 65: automatic enrollment in Part A and Part B.
• Already receiving SSDI for 24 months: automatic enrollment.
• Everyone else — including anyone deferring Social Security past 65 — must actively enroll through the Social Security Administration.

Once you're eligible, the next decision is coverage design: Original Medicare with a supplement, or a Medicare Advantage plan that bundles Parts A, B, and usually D into a single network-based product.

Medicare and Medicaid together (dual eligible)

Roughly 12 million Americans qualify for both Medicare and Medicaid. Medicaid income and asset thresholds vary by state and program tier (QMB, SLMB, QI). Dual-eligible beneficiaries pay little to no Medicare cost-sharing and typically qualify for the Extra Help subsidy on Part D. State Health Insurance Assistance Programs (SHIPs) can walk you through eligibility for free.

Non-citizen and residency rules

Non-citizens legally residing in the U.S. must be lawfully present for 5 continuous years and be 65 or older to buy premium Part A and Part B. There is no free Part A for those who have not accrued the required work quarters through their own or a spouse's employment.

Eligible and ready to compare? Start with the Medicare Plan Finder guide, or confirm what coverage you already have.

Frequently asked questions

Who is eligible for Medicare?

US citizens and qualifying lawful permanent residents aged 65 and older, people under 65 who have received Social Security disability benefits for 24 months, and people with end-stage renal disease or ALS regardless of age.

Do I have to pay for Part A?

Not if you or a spouse paid Medicare payroll taxes for at least 40 quarters, roughly ten years of work. With fewer quarters you can still buy Part A, at a monthly premium that scales with how many quarters you have.

Am I enrolled in Medicare automatically?

If you are already receiving Social Security or Railroad Retirement benefits when you turn 65, Parts A and B start automatically. If you are not, you must actively enroll through the Social Security Administration during your Initial Enrollment Period.

Once eligible, how do I choose a plan?

Decide first between Original Medicare with a supplement and drug plan, or a Medicare Advantage plan, then compare specific plans in the Medicare Plan Finder using your prescriptions, pharmacies and doctors.

This is journalism, not enrollment advice. For personalized eligibility review, contact your State Health Insurance Assistance Program (SHIP) or the Social Security Administration.