When You Become Eligible for Medicare

You can sign up for Medicare at 65, or earlier if you have certain disabilities or conditions

Medicare may be able to access begins at age 65 for most people. You do not have to wait for a birthday or a specific date — you can sign up during the three months before you turn 65, the month you turn 65, or the three months after. If you miss that window, you can still sign up later, but you may pay a penalty on your premiums for as long as you have Medicare.

You can also become may be able to access before 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have End-Stage Renal Disease (ESRD) — permanent kidney failure requiring dialysis or transplant — or ALS (amyotrophic lateral sclerosis). These routes have different timing and different rules about when to sign up.

The key is understanding which path applies to you and when your coverage actually starts, because the dates are not always the same as the dates you sign up.

Key Takeaways

Most people become may be able to access at 65, and you can sign up in the three months before, during, or three months after the month you turn 65.
If you receive SSDI, you become may be able to access after 24 months on the program, regardless of your age.
If you have ESRD or ALS, you can sign up when ready, and coverage starts the month after you sign up or the month your condition began, whichever is later.
Missing your initial sign-up window triggers a permanent penalty on Part B and Part D premiums unless you have a valid reason for the delay.
You sign up through Social Security, Medicare.gov, or by calling 1-800-MEDICARE, and the process takes about 15 minutes.

Age 65: The standard enrollment window

If you are turning 65 and do not have a disability or medical condition that qualifies you earlier, your Initial Enrollment Period (IEP) runs for seven months: three months before the month you turn 65, the month itself, and three months after.

Your coverage start date depends on when you sign up within that window. If you sign up in the three months before you turn 65, coverage starts the month you turn 65. If you sign up during the month you turn 65, coverage starts the following month. If you sign up in the three months after, coverage starts one to three months after you sign up, depending on which month you submit your request.

You do not need to do anything on your 65th birthday itself. You have a full seven-month window, and many people sign up two or three months before to may support coverage starts smoothly.

SSDI: Becoming may be able to access before 65

If you have been receiving SSDI for 24 consecutive months, you become may be able to access for Medicare at the start of the 25th month, regardless of your age. You do not have to be 65. Social Security will contact you automatically when you reach the 24-month mark and send you information about signing up.

Your coverage can start as early as the month after you become may be able to access. You have a seven-month window to sign up without penalty — the month you become may be able to access, plus three months before and three months after — but Social Security usually handles the enrollment for you if you do not decline it.

If you are working and earning above the substantial gainful activity (SGA) limit while on SSDI, contact Social Security before signing up for Medicare, because your SSDI status may change and affect your Medicare timeline.

ESRD and ALS: when ready may be able to access

If you have End-Stage Renal Disease requiring dialysis or a transplant, you become may be able to access for Medicare when ready upon diagnosis, regardless of age. You can sign up right away, and coverage starts the month after you sign up or the month your treatment began, whichever is later.

If you have ALS, you become may be able to access when ready upon diagnosis as well. Coverage starts the month after you sign up. You do not have to wait 24 months or reach 65.

For both conditions, you sign up through Social Security, Medicare.gov, or by phone at 1-800-MEDICARE. Bring documentation of your diagnosis — a letter from your nephrologist for ESRD, or from your neurologist for ALS. There is no penalty for signing up at any time if you have either condition.

What happens if you miss your enrollment window

If you do not sign up during your Initial Enrollment Period and you do not have a valid reason for the delay, you will pay a late enrollment penalty on your Part B premium (medical insurance) and Part D premium (prescription drug coverage) for as long as you have Medicare.

The Part B penalty is 10 percent of the standard premium for each full year you were may be able to access but not signed up. The Part D penalty is 1 percent of the national average premium for each month you were may be able to access but not signed up. These penalties are permanent — they do not go away after a certain number of years.

A valid reason for late sign-up includes losing employer health coverage, moving out of the United States and returning, or a documented error by Social Security or Medicare. If you believe you have a valid reason, you can request a Special Enrollment Period (SEP) when you sign up, and Social Security or Medicare will review your case.

How to sign up and what you need

You can sign up for Medicare through three routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online is usually fastest — the process takes about 15 minutes.

You will need your Social Security number, proof of citizenship or legal residency (your birth certificate, passport, or naturalization papers), and proof of age. If you are signing up for Part B (medical insurance), you may also need information about any current health coverage you have, such as an employer plan or COBRA.

If you are already receiving Social Security benefits, you do not need to provide proof of age or citizenship — Social Security has that information on file. You can sign up online or by phone without visiting an office.

Coverage that starts before you sign up

If you are still working at 65 and your employer has 20 or more employees, you can delay signing up for Part B without penalty. Your employer coverage is considered primary, and Medicare is secondary. You have eight months after you leave your job or your coverage ends to sign up for Part B without penalty.

If you are covered by a spouse's employer plan, the same rule applies — you can delay Part B sign-up. However, you should still sign up for Part A (hospital insurance) at 65, because Part A is free for most people and has no penalty for late sign-up.

If you are not sure whether your employer coverage qualifies you to delay Part B, contact your benefits administrator or call 1-800-MEDICARE and ask. Getting this wrong can cost you thousands in penalties over time.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

Yes, if you have SSDI (after 24 months), ESRD, or ALS. Otherwise, you can sign up starting three months before you turn 65. You cannot sign up more than three months early for age-based may be able to access.

What if I am still working at 65 and have health insurance through my job?

You can delay Part B sign-up without penalty if your employer has 20 or more employees. You should still sign up for Part A at 65 because it is free and has no late penalty. When you leave your job, you have eight months to sign up for Part B.

Do I have to sign up for all parts of Medicare at once?

No. You can sign up for Part A and Part B at different times. Part D (prescription drug coverage) has its own enrollment window — you can sign up anytime, but you pay a penalty if you go 63 days or more without coverage and then sign up later.

What if Social Security made a mistake and I missed my enrollment window?

You can request a Special Enrollment Period and ask for the penalty to be waived. Contact Social Security or Medicare with documentation of the error. They will review your case, but approval is not may provide.

Does Medicare start the same month I sign up?

Not always. If you sign up before the month you turn 65, coverage starts the month you turn 65. If you sign up during or after, there is a one- to three-month delay. For ESRD and ALS, coverage starts the month after you sign up or the month your condition began, whichever is later.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.