When You Can Sign Up for Medicare: Age Requirements and Timing

You can sign up for Medicare at 65, or earlier if you have a disability or end-stage renal disease

Most people become may be able to access for Medicare at age 65, regardless of income or health history. You do not have to wait until you retire. If you are already receiving Social Security benefits, Medicare enrollment happens automatically three months before your 65th birthday. If you are not yet taking Social Security, you will need to sign up for Medicare yourself during your enrollment window.

Some people can sign up before 65. You may be may be able to access at any age if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). Each of these situations has different rules about when coverage starts.

Missing your enrollment window can result in permanent penalties on your premiums, so knowing your specific enrollment dates matters. The rules differ depending on whether you are working, receiving benefits, or have a disability.

Key Takeaways

Most people sign up for Medicare at 65, and if you receive Social Security, enrollment is automatic three months before your birthday.
You can sign up earlier than 65 if you have been on SSDI for 24 months, have end-stage renal disease, or have ALS.
Your enrollment window is seven months long and centered on your birthday month — three months before, the month itself, and three months after.
If you miss your window and do not have a may have access to reason, you will pay a permanent 10% increase on your Part B premium for each year you were not enrolled.
You must actively sign up for Medicare unless you are already receiving Social Security benefits, in which case enrollment is automatic.

Enrollment at 65: The standard timeline and automatic enrollment

Your Initial Enrollment Period (IEP) is seven months long: three months before the month you turn 65, the month itself, and three months after. For example, if you turn 65 in June, your window runs from March through September. During this time, you can sign up for any part of Medicare without penalty.

If you are receiving Social Security retirement, spousal, survivor, or disability benefits, Medicare enrollment is automatic. You will receive your Medicare card in the mail about two weeks before your 65th birthday. You do not need to do anything. If you want to decline Part B (medical insurance) because you have employer coverage, you must contact Social Security in writing before your coverage starts.

If you are not yet receiving Social Security, you must sign up for Medicare yourself. You can do this online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. Signing up for Medicare does not automatically enroll you in Social Security — these are two separate processes.

Signing up before 65: Disability, ESRD, and ALS

You can sign up for Medicare before 65 if you have been receiving SSDI for at least 24 consecutive months. Your coverage typically begins on the 25th month of your disability benefits. You do not need to explore separately — Social Security automatically enrolls you in Medicare Parts A and B.

If you have end-stage renal disease (ESRD) requiring dialysis or a kidney transplant, you can sign up for Medicare at any age. Your coverage can start the first day of the month you begin dialysis treatment, or the month of your transplant. You will need to provide medical documentation of your ESRD diagnosis to Medicare.

If you have amyotrophic lateral sclerosis (ALS), you become may be able to access for Medicare when ready upon approval for SSDI, without waiting the usual 24-month period. Your coverage begins the same month your SSDI benefits start.

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 may have access to reason for a late enrollment, you will face a permanent penalty. Your Part B premium increases by 10% for each full 12-month period you were not enrolled after you became may be able to access. This penalty stays with you for life, even after you finally sign up.

For example, if you turn 65 in 2024 and do not sign up until 2026, you owe two years of penalties — a 20% increase on your Part B premium forever. The penalty applies only to Part B; Part A (hospital insurance) has no penalty if you have paid Medicare taxes for at least 30 quarters.

A may have access to reason for late enrollment means you had employer coverage through your own job or your spouse's job, or you were working outside the United States. If you had one of these situations, you can sign up without penalty during an eight-month window after your coverage ends. You will need to provide proof — usually a letter from your employer or health plan stating when your coverage ended.

Enrollment periods after your initial window closes

Once your Initial Enrollment Period ends, you enter the General Enrollment Period, which runs January 1 through March 31 each year. You can sign up during this time, but any late enrollment penalty applies unless you have a may have access to reason.

If your life circumstances change — you lose employer coverage, move to a new state, or experience another may have access to event — you may be may be able to access for a Special Enrollment Period lasting eight months. may have access to events include losing employer health coverage, becoming a U.S. citizen, or having Medicaid coverage end. You will need to contact Medicare to report the event and request the special window.

Working past 65 and employer coverage

If you are still working at 65 and have health insurance through your employer, you may not need to sign up for Medicare Part B right away. If your employer has 20 or more employees, your employer coverage is primary, and Medicare is secondary. You can delay Part B enrollment without penalty as long as you are actively working and covered by that employer plan.

Once you leave that job or your coverage ends, you have eight months to sign up for Part B without penalty. You will need to provide your employer with a letter stating that you had group health coverage through your job. Keep this documentation — you may need it to prove you had a may have access to reason for late enrollment.

If your employer has fewer than 20 employees, Medicare becomes primary at 65 even if you are working. In this case, you should sign up for Medicare during your Initial Enrollment Period to avoid penalties.

How to sign up and what documents you need

You can sign up for Medicare in three ways: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. The online method is fastest — you can complete it in about 15 minutes if you have your information ready.

Have these documents available when you sign up: your Social Security number, proof of citizenship or legal residency (passport, birth certificate, or naturalization papers), and proof of residence (utility bill, lease, or mortgage statement dated within the past two months). If you are signing up for Part B and have employer coverage, bring a letter from your employer or health plan showing your coverage dates.

If you are signing up due to a disability or ESRD, you will need medical documentation. Social Security will request this directly if you are explore for SSDI. If you have ESRD, contact your dialysis center or transplant center — they can help you gather the required medical records.

Frequently Asked Questions

Do I have to sign up for Medicare at 65 if I am still working?

If your employer has 20 or more employees and you have health coverage through that job, you can delay Part B without penalty. However, you should still sign up for Part A (hospital insurance) at 65 because it is free and covers inpatient care. Once you leave your job, you have eight months to sign up for Part B.

What if I turn 65 outside the United States?

You can still sign up for Medicare during your Initial Enrollment Period. Contact Social Security by phone or mail — you do not need to be in the U.S. to enroll. If you are living abroad, be aware that Original Medicare does not cover care outside the U.S., though some Medicare Advantage plans offer limited international coverage.

Can I sign up for Medicare before my 65th birthday?

Your Initial Enrollment Period begins three months before your 65th birthday, so yes — you can sign up as early as three months before you turn 65. Signing up early does not change your coverage start date; it begins the month you turn 65 regardless of when you enroll during your window.

What if I miss my enrollment window but have a good reason?

If you had employer coverage through your job or your spouse's job, or you were working outside the U.S., you have eight months after that coverage ends to sign up without penalty. Contact Medicare at 1-800-MEDICARE and explain your situation. You will need to provide proof from your employer or health plan.

Does signing up for Medicare affect my Social Security benefits?

No. Signing up for Medicare is separate from claiming Social Security retirement benefits. However, if you are already receiving Social Security, Medicare enrollment is automatic at 65. If you have not yet claimed Social Security, you can sign up for Medicare without affecting when you claim retirement benefits.

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.