Medicare covers people 65 and older, some younger people with disabilities, and people with end-stage renal disease

Medicare is a federal health insurance program run by the Centers for Medicare & Medicaid Services (CMS). The program has four main parts — Part A (hospital insurance), Part B (medical insurance), Part D (prescription drug coverage), and Part C (Medicare Advantage plans) — and each covers different services. But the first question is always: does Medicare cover you at all?

The broadest group covered is people age 65 and older. You do not have to be retired, and you do not have to be poor. If you are 65 or older and a U.S. citizen or permanent resident who has lived in the country for at least five years, you can enroll in Medicare. A second group is people under 65 who have received Social Security Disability Insurance (SSDI) benefits for at least 24 months. A third group is people of any age with end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or transplant. A fourth, smaller group is people with amyotrophic lateral sclerosis (ALS), who become covered when ready upon approval for SSDI without the 24-month wait.

Key Takeaways

  • You become covered by Medicare automatically at 65 if you are already receiving Social Security retirement benefits; otherwise you must enroll during your initial enrollment period.
  • People under 65 who have received SSDI for 24 months, or who have ESRD or ALS, may be covered regardless of age.
  • Enrollment important date matter: missing your initial enrollment period can result in permanent late-enrollment penalties on your premiums.
  • Medicare Part A (hospital) and Part B (doctor visits) are the foundation; Part D (prescription drugs) and Part C (Medicare Advantage) are optional add-ons with their own enrollment rules.
  • Medicaid (a separate program run by states) covers some people Medicare does not, and some people may have access to for both programs at the same time.

Age 65 and older: automatic or manual enrollment

If you are 65 or older, a U.S. citizen, and a permanent resident for at least five years, you are covered by Medicare. But "covered" does not mean you are automatically signed up. If you are already receiving Social Security retirement benefits when you turn 65, Medicare Part A and Part B enroll you automatically — you will receive your Medicare card in the mail about three months before your 65th birthday. You do not have to do anything.

If you are not yet receiving Social Security retirement benefits at 65, you must enroll yourself during your initial enrollment period. This period runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. For example, if you turn 65 in June, your initial enrollment period is March through September. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. If you miss this window, you can still enroll later, but you will pay a permanent penalty on your Part B premium — roughly 10 percent more for each year you delayed.

People under 65 with disabilities: the 24-month rule and exceptions

If you are under 65 and receiving SSDI benefits, you become covered by Medicare after you have been on SSDI for 24 months. The 24 months is measured from the month you started receiving SSDI payments, not from the month you applied. So if you were approved for SSDI in January 2023 and your first payment arrived in March 2023, your 24-month period ends in March 2025, and Medicare coverage begins in April 2025.

Two conditions skip the 24-month wait entirely. If you have been approved for SSDI because of ALS (amyotrophic lateral sclerosis), you become covered by Medicare when ready — no waiting period. If you have end-stage renal disease (ESRD) and need dialysis or a kidney transplant, you also become covered when ready, regardless of age or whether you receive SSDI. For ESRD, coverage typically begins the first day of the month in which your dialysis or transplant occurs, or the first day of the month you are deemed to need dialysis.

End-stage renal disease and other conditions

End-stage renal disease (ESRD) is permanent kidney failure. If your kidneys can no longer filter waste and excess water from your blood, you need either dialysis (a machine that does the filtering) or a kidney transplant. Medicare covers you as soon as you begin treatment, even if you are 30 years old and have never paid Medicare taxes. Your coverage begins on the first day of the month your treatment starts, or the first day of the month you are determined to need treatment, whichever is earlier.

ALS (amyotrophic lateral sclerosis, also called Lou Gehrig's disease) is a progressive neurological disease that weakens muscles over time. If you are approved for SSDI because of ALS, Medicare covers you from the month you are approved — you do not wait 24 months. This is the only condition that receives this exception.

How to check your coverage status

You can check whether you are currently covered by Medicare by creating an account on Medicare.gov and signing in, or by calling 1-800-MEDICARE. Have your Social Security number ready. The phone line is open Monday through Friday, 8 a.m. to 8 p.m. Eastern time, and Saturday 8 a.m. to 4 p.m. Eastern time. If you are deaf or hard of hearing, you can use the TTY number 1-877-486-2048.

If you are not yet 65 and believe you may be covered because of a disability or ESRD, contact Social Security directly at 1-800-772-1213 to confirm your SSDI status and coverage date. Social Security handles SSDI approvals and can tell you the exact month your 24-month period ends, or confirm whether you have an exception like ALS.

Medicare and Medicaid: two different programs that sometimes overlap

Medicare and Medicaid are separate programs run by different agencies. Medicare is federal and covers people 65 and older, some younger people with disabilities, and people with ESRD. Medicaid is run by each state and covers people with low income and few assets — the income and asset limits vary by state. Some people are covered by both programs at the same time; these people are called "dual may be able to access."

If you are 65 or older and have low income, you may be covered by both Medicare and your state's Medicaid program. Medicaid can help pay your Medicare premiums and cover services Medicare does not, like long-term care. If you think you might be covered by Medicaid, contact your state's Medicaid office or call 211 to find your local office. Each state has different income limits, so there is no single answer to whether you may have access to.

What happens after you confirm coverage

Once you know you are covered by Medicare, you have decisions to make about which parts to enroll in. Part A (hospital insurance) and Part B (medical insurance) are the foundation. Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and home health services. Part B covers doctor visits, outpatient services, and medical equipment. Most people pay a monthly premium for Part B; Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years.

Part D (prescription drug coverage) and Part C (Medicare Advantage) are optional. Part D is added to Original Medicare (Parts A and B) and covers prescription medications. Part C is an alternative to Original Medicare — it is a private insurance plan that covers everything Parts A and B cover, usually with lower out-of-pocket costs but a narrower network of doctors. Each has its own enrollment important date and penalties for late enrollment. If you are automatically enrolled at 65, you are enrolled in Parts A and B only; you must choose Part D and Part C separately.

Frequently Asked Questions

Do I have to be a U.S. citizen to get Medicare?

You must be a U.S. citizen or a permanent resident (green card holder) who has lived in the United States for at least five years. If you are a permanent resident, you will need to show proof of your status when you enroll.

What if I am still working at 65?

You can still enroll in Medicare at 65 even if you are working. If you have health insurance through your employer, you may want to delay Part B enrollment without penalty if your employer has 20 or more employees — but you must enroll in Part A. Talk to your employer's benefits office about how Medicare and your work insurance interact.

Can I lose my Medicare coverage?

Medicare coverage for people 65 and older does not end. For people under 65 on SSDI, coverage continues as long as you remain on SSDI. If your SSDI is terminated because your condition improved, your Medicare coverage ends, though you may have a grace period to transition to other insurance.

What if I am not sure whether I have ESRD?

Your doctor can tell you whether your kidney function qualifies as end-stage renal disease. If you are on dialysis or have had a kidney transplant, you almost certainly have ESRD. Contact Medicare at 1-800-MEDICARE to discuss your specific situation, or ask your nephrologist (kidney doctor) to help you understand your diagnosis.

Do I pay for Medicare if I am covered?

Most people pay a monthly premium for Part B (medical insurance). Part A is usually free. Part D (prescription drugs) and Part C (Medicare Advantage) have their own premiums that vary by plan. You will also pay deductibles and copayments when you use services. Income-based programs can help pay these costs if your income is low.