The Main Groups Covered by Medicare

Medicare covers people in four main categories: anyone 65 or older, people under 65 with certain disabilities, people with end-stage renal disease (permanent kidney failure), and people with ALS (Lou Gehrig's disease). You do not need to be retired or poor to get Medicare—age or a specific medical condition is what matters. Most people become covered automatically when they turn 65 if they have already paid into Social Security for at least 10 years.

The program is run by the Centers for Medicare & Medicaid Services (CMS), a federal agency. It is not means-tested, meaning your income or savings do not disqualify you. However, your income does affect how much you pay for premiums and out-of-pocket costs once you are covered.

Key Takeaways

  • You become covered at 65 automatically if you have paid into Social Security for at least 10 years, with no process needed.
  • People under 65 can get Medicare if they receive Social Security Disability Insurance (SSDI) for at least 24 months, or if they have end-stage renal disease or ALS.
  • Non-citizens can get Medicare at 65 if they have been a permanent resident for at least five years and meet the work history requirement.
  • If you do not sign up during your initial enrollment window, you may pay a permanent penalty on your premiums.

Automatic Coverage at Age 65

If you are receiving Social Security benefits when you turn 65, Medicare Part A (hospital insurance) and Part B (medical insurance) start automatically on the first day of the month you turn 65. You do not need to do anything. CMS will mail you a Medicare card about three months before your 65th birthday.

If you are not yet taking Social Security at 65, you must contact Social Security to sign up for Medicare. You can do this online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office. If you delay signing up and do not have a valid reason (called a "may have access to event"), you will pay a 10 percent penalty on Part B premiums for as long as you have Medicare.

The work history requirement is 40 quarters of coverage—roughly 10 years of paid work where you paid Social Security taxes. You do not have to have worked those 10 years consecutively, and you do not have to have worked recently. If you are a non-citizen, you must also have been a permanent resident (green card holder) for at least five years.

Coverage Before 65 Through Disability

People under 65 can get Medicare if they receive Social Security Disability Insurance (SSDI) for at least 24 months. SSDI is a separate program from Medicare; you explore for SSDI through Social Security, and after 24 months of receiving it, Medicare coverage begins automatically. You do not explore for Medicare separately in this case.

The 24-month waiting period starts from the month you are approved for SSDI, not from when you explore. During those 24 months, you may be covered by Medicaid instead, depending on your state. Once the 24 months pass, you get both SSDI and Medicare.

To get SSDI, you must have a medical condition that prevents you from working and is expected to last at least 12 months or result in death. You also need work history—the amount varies by age, but younger workers typically need fewer quarters of coverage than older workers. A Social Security representative can tell you whether you have enough work history before you explore.

End-Stage Renal Disease and ALS

People of any age with end-stage renal disease (ESRD)—permanent kidney failure requiring dialysis or a transplant—become covered by Medicare when ready upon diagnosis. You do not have to wait 24 months. You must be a U.S. citizen or permanent resident, but there is no work history requirement.

People with ALS (amyotrophic lateral sclerosis, also called Lou Gehrig's disease) also get Medicare when ready upon diagnosis, regardless of age or work history. Like ESRD, you must be a U.S. citizen or permanent resident.

For both conditions, Medicare coverage begins in the month you are diagnosed. You will receive a Medicare card in the mail. If you are also receiving SSDI or SSI (Supplemental Security Income), Social Security will coordinate your enrollment automatically.

What Happens if You Miss Your Enrollment Window

Your initial enrollment period is the seven-month window that includes the month you turn 65 and the three months before and after. If you do not sign up for Part B during this window and you do not have other may have access to coverage (like employer insurance), you will pay a permanent 10 percent surcharge on your Part B premium for as long as you have Medicare.

There are exceptions. If you are still working and covered by your employer's health plan, you can delay Part B without penalty. You have eight months after you leave that job or lose that coverage to sign up without penalty. You must tell Social Security about your employer coverage when you explore.

If you miss your window and do not have a may have access to reason, you can still sign up, but the penalty applies. There is no way to remove it once it is in place, even if you pay it for years and then drop coverage.

Immigrants and Non-Citizens

Non-citizens can get Medicare at 65 if they have been a permanent resident (green card holder) for at least five years and meet the work history requirement (40 quarters of coverage). The five years do not have to be consecutive, and time spent as a permanent resident counts toward the requirement.

Undocumented immigrants are not covered by Medicare. Refugees and asylees are treated as permanent residents for Medicare purposes once their status is granted, and the five-year clock starts from the date their status was approved.

If you are a non-citizen and unsure about your status, Social Security can review your case. Bring your immigration documents when you explore.

Government Employees and Railroad Workers

Most federal government employees hired after 1983 pay into Medicare and become covered at 65 like other workers. Federal employees hired before 1984 may have different rules—some are not covered by Medicare at all and instead receive benefits through the Federal Employees Health Benefits Program (FEHB).

Railroad workers are covered by a separate system called the Railroad Retirement Board (RRB) rather than Social Security. They become covered at 65 if they have worked in the railroad industry for at least 10 years. The process is similar to Social Security, but you contact the RRB instead of Social Security.

Frequently Asked Questions

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

No. You can get Medicare at 65 if you are a permanent resident and have been one for at least five years, plus you have 40 quarters of work history. Undocumented immigrants are not covered. Refugees and asylees are treated as permanent residents once their status is granted.

What if I worked outside the United States?

Work you did outside the U.S. generally does not count toward the 40 quarters requirement, even if you paid taxes. However, some countries have agreements with the U.S. that allow certain work to count. Contact Social Security to ask whether your foreign work history qualifies.

Can my spouse get Medicare based on my work history?

Yes. A spouse 62 or older can get Medicare at 65 based on the other spouse's work history, even if they did not work themselves or did not work long enough to may have access to on their own. You must be married and your spouse must have 40 quarters of coverage.

What if I am still working at 65?

You can delay signing up for Part B without penalty if you are covered by your employer's health plan. Once you leave that job or lose that coverage, you have eight months to sign up without penalty. Tell Social Security about your employer coverage when you explore.

How do I know if I have 40 quarters of work history?

Create an account at ssa.gov and view your Social Security statement, which shows your work history and quarters earned. You can also call Social Security at 1-800-772-1213 and ask a representative to review your record.