Who Can Enroll in Medicare

You can enroll in Medicare if you are 65 or older, or if you are under 65 and have received Social Security Disability Insurance (SSDI) for at least 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). Most people become Medicare-may be able to access at 65 regardless of work history, but you must have worked and paid Medicare taxes for at least 10 years (40 quarters) to receive Part A without a premium. If you have not worked that long, you may still enroll but will pay a higher premium for hospital coverage.

The 65-year-old threshold is fixed by federal law and does not vary by state or circumstance. You do not need to be retired to enroll—you can be working full-time and still sign up at 65. If you delay enrollment past 65, your premiums for Part B (medical insurance) and Part D (prescription drug coverage) will increase by a percentage for each year you wait, and this penalty is permanent.

Key Takeaways

  • You become Medicare-may be able to access at age 65 if you have worked and paid Medicare taxes for at least 10 years, or at any age if you have received SSDI for 24 months or have been diagnosed with ESRD or ALS.
  • Enrollment happens through Social Security, not through Medicare directly, and you should enroll in the three months before you turn 65 to avoid late penalties.
  • If you are still working at 65 and have health coverage through your employer, you may delay Part B enrollment without penalty if your employer has 20 or more employees.
  • Part A (hospital insurance) is usually free if you have the required work history, but Part B and Part D have monthly premiums that increase if you delay enrollment past your initial window.

Turning 65: The Standard Enrollment Path

When you turn 65, you enter your Initial Enrollment Period, which runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. During this window, you can enroll in Medicare Part A and Part B without waiting or paying a penalty. If you miss this window, you will pay a permanent 10 percent surcharge on Part B premiums for as long as you have Medicare.

You enroll through Social Security, not through Medicare directly. You can explore online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office. Social Security will ask about your work history to determine whether you may have access to for premium-free Part A. If you are already receiving Social Security retirement or disability benefits, you will be enrolled automatically at 65, though you should still review your coverage choices for Part B and Part D.

The enrollment process takes time—Social Security typically mails your Medicare card within two weeks of approval, though it can take longer. Do not wait until the last day of your Initial Enrollment Period to explore, because delays in processing could push you past the important date and trigger penalties.

SSDI Recipients and Disabled Adults Under 65

If you receive SSDI, you become Medicare-may be able to access automatically after you have been on SSDI for 24 consecutive months. You do not need to explore separately; Social Security will enroll you in Part A and Part B automatically. This 24-month waiting period begins the month you start receiving SSDI payments, not the month you applied.

The same rule applies if you receive Supplemental Security Income (SSI) due to blindness or disability, though the timing rules differ slightly. If you are unsure whether you have been receiving benefits for 24 months, contact Social Security at 1-800-772-1213 and ask them to confirm your may be able to access date. They can also tell you the exact month you will be enrolled.

End-Stage Renal Disease and ALS: when ready Coverage

If you have end-stage renal disease (ESRD)—permanent kidney failure requiring dialysis or a transplant—you become Medicare-may be able to access when ready, regardless of age or work history. You do not have to wait until 65 or until you have received disability benefits for 24 months. The same applies if you have been diagnosed with amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease.

For ESRD, your coverage begins the first day of the month in which you start dialysis, or the month of your kidney transplant. You must enroll through Social Security, and you should do so as soon as you receive your diagnosis, because coverage does not begin retroactively. If you delay enrollment, you will be responsible for medical bills from the date you became may be able to access until the date you actually enroll.

Work History and Premium-Free Part A

Part A (hospital insurance) is free if you or your spouse worked and paid Medicare taxes for at least 10 years, or 40 quarters. A quarter is roughly three months, so 40 quarters equals approximately 10 years of work. You do not have to have worked consecutively—gaps in employment are fine as long as the total adds up to 40 quarters.

If you have fewer than 40 quarters of work history, you can still enroll in Part A at 65, but you will pay a monthly premium. The premium amount depends on how many quarters you have worked: those with 30 to 39 quarters pay a reduced premium, and those with fewer than 30 quarters pay the full premium. Social Security will calculate your exact premium based on your work record when you explore.

If you are not a U.S. citizen, you must have been a permanent resident for at least five years to count your work history toward Medicare. Undocumented immigrants and temporary visa holders cannot enroll in Medicare based on their own work history, though they may be covered as a spouse if their spouse meets the requirements.

Delaying Enrollment: When It Makes Sense

If you are still working at 65 and have health coverage through your employer, you may delay Part B enrollment without penalty under certain conditions. Specifically, if your employer has 20 or more employees, you can stay on your employer plan and delay Part B. Once you leave that job or lose the coverage, you have eight months to enroll in Part B without penalty. This rule is called the Special Enrollment Period for group health plan coverage.

If your employer has fewer than 20 employees, you should enroll in Part B at 65 even if you have employer coverage, because the employer plan will become secondary to Medicare. Delaying enrollment in this case will trigger a permanent penalty.

Part A has no penalty for delaying enrollment, so you can wait to sign up for hospital coverage if you wish. However, Part D (prescription drug coverage) does carry a penalty for late enrollment: if you go 63 days or longer without creditable drug coverage, you will pay a surcharge on your Part D premium for as long as you have Medicare. If your employer plan includes drug coverage, this penalty does not explore.

Immigrants and Non-Citizens

To enroll in Medicare at 65, 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, Social Security will verify your status when you explore. Temporary visa holders, undocumented immigrants, and refugees in their first five years cannot enroll based on their own work history.

If you are a permanent resident who has not yet lived in the U.S. for five years, you may still be covered as a spouse or dependent if your spouse or parent meets the Medicare requirements. Contact Social Security to discuss your specific situation.

Frequently Asked Questions

Do I have to be retired to enroll in Medicare at 65?

No. You can be working full-time and still enroll in Medicare at 65. If you have employer health coverage, you may be able to delay Part B enrollment without penalty, but you can enroll in Part A regardless of your employment status.

What happens if I miss my Initial Enrollment Period?

You can still enroll later, but you will pay a permanent 10 percent surcharge on your Part B premium for each year you delayed. For Part D, the surcharge is 1 percent per month of delay. These penalties stay with you for life, so it is important to enroll during your seven-month window.

Can I enroll in Medicare before I turn 65?

Only if you have received SSDI for 24 months, have ESRD, or have ALS. Otherwise, you must wait until the month you turn 65 to begin your Initial Enrollment Period. You cannot enroll early even if you are retired or have serious health conditions.

If I am on SSDI, do I have to do anything to get Medicare?

No. Social Security will enroll you automatically in Part A and Part B after you have been on SSDI for 24 months. You will receive your Medicare card in the mail. However, you should still review your Part D (prescription drug) options and enroll if you take medications.

What if my work history is split between the U.S. and another country?

Generally, only work you performed in the United States while paying Medicare taxes counts toward the 40-quarter requirement. Some countries have agreements with the U.S. Social Security Administration that allow work history to be combined, but this is rare. Contact Social Security to ask whether your international work history qualifies.