The Age When You Can Enroll in Medicare

You can enroll in Medicare starting at age 65

Medicare may be able to access begins the month you turn 65, regardless of whether you are still working. You do not have to retire to sign up. The program has four parts — Part A (hospital insurance), Part B (medical insurance), Part D (prescription drug coverage), and Part C (Medicare Advantage, an alternative to Parts A and B) — and enrollment rules differ slightly for each one.

Most people become automatically enrolled in Parts A and B if they are already receiving Social Security benefits when they turn 65. If you are not yet taking Social Security, you will need to contact Medicare directly to enroll. The enrollment window is three months before your 65th birthday, the month you turn 65, and three months after — a total of seven months. Missing this window can mean paying a permanent penalty on your premiums.

Some people can enroll before 65 if they have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if they have end-stage renal disease or ALS. These are narrow exceptions; most people must wait until 65.

Key Takeaways

You become may be able to access for Medicare at age 65, and enrollment opens three months before your birthday.
If you receive Social Security, you are usually enrolled automatically in Parts A and B at 65 — you do not need to do anything.
If you do not receive Social Security, you must contact Medicare yourself during your enrollment window or face a permanent premium penalty.
People on SSDI for 24 months, or with end-stage renal disease or ALS, can enroll before 65.
Part D (prescription drug) enrollment has the same age rule but a separate enrollment important date — missing it also triggers a lifetime penalty.

What happens if you are still working at 65

Working past 65 does not delay your Medicare enrollment. You can enroll at 65 even if you are employed full-time and covered by your employer's health plan. However, if your employer has 20 or more employees, your group health plan is considered primary — it pays first — and Medicare pays second. You can delay enrolling in Part B without penalty as long as you have this coverage, but you should still enroll in Part A, which has no premium for most people.

Once you leave your job or lose employer coverage, you have a Special Enrollment Period of eight months to sign up for Part B without penalty. If you miss this window, you will pay a 10 percent penalty on your Part B premium for each year you were may be able to access but not enrolled. This penalty is permanent and compounds annually, so delaying enrollment can become expensive.

Automatic enrollment versus manual enrollment

If you are receiving Social Security retirement benefits, Social Security Disability Insurance, or Railroad Retirement Board benefits before you turn 65, Medicare will enroll you automatically in Parts A and B. You will receive a Medicare card in the mail about two weeks before your 65th birthday. You do not need to do anything.

If you are not receiving any of these benefits, you must contact Medicare yourself. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage. Enrollment takes about 10 minutes online.

Even if you are automatically enrolled in Parts A and B, you must enroll separately in Part D (prescription drug coverage) if you want it. Part D has its own enrollment important date — the same seven-month window around your 65th birthday — and missing it also results in a permanent penalty.

Part C (Medicare Advantage) enrollment rules

Part C, also called Medicare Advantage, is an alternative way to receive Medicare benefits through a private insurance company. You can enroll in Part C during the same seven-month window as Parts A and B (three months before your 65th birthday through three months after). However, Part C has an additional enrollment period: the Annual Enrollment Period, which runs October 15 through December 7 each year. You can switch between Part C plans or return to Original Medicare during this window.

If you miss your initial enrollment window at 65 and do not have creditable coverage (employer or union coverage that is at least as good as Medicare), you will pay a permanent penalty if you later enroll in Part C. This penalty is calculated differently than Part B or Part D penalties, so it is worth understanding your options before your birthday.

How to prepare before your 65th birthday

Start three months before you turn 65. If you receive Social Security, SSDI, or Railroad Retirement benefits, you do not need to do anything — just watch for your Medicare card. If you do not receive these benefits, contact Medicare at 1-800-MEDICARE or visit Medicare.gov to enroll.

Gather your documents: your Social Security number, proof of U.S. citizenship or legal residency (passport, birth certificate, or naturalization papers), and information about any current health coverage. If you are still working and covered by an employer plan, have that policy number and your employer's name ready.

Review your prescription drug needs and compare Part D plans if you want drug coverage. You can use the Medicare Plan Finder tool at Medicare.gov to see which plans cover your medications and what they cost. Part D premiums and coverage vary widely by plan and by year, so comparing before you enroll can save money.

Penalties for late enrollment

Missing your enrollment window triggers permanent penalties on your premiums. For Part B, the penalty is 10 percent of the standard premium for each year you were may be able to access but not enrolled. For Part D, the penalty is 1 percent of the national average premium for each month you were may be able to access but not enrolled. These penalties stay with you for life, even if you later switch plans.

The only way to avoid these penalties is to have creditable coverage — health insurance that is at least as good as Medicare — during the time you were may be able to access but not enrolled. Creditable coverage includes employer plans, TRICARE, the Veterans Health Administration, or certain other group plans. If you had creditable coverage, you can show proof to Medicare and avoid the penalty. You will need documentation from your previous insurer stating that the coverage was creditable.

Special situations: disability, ESRD, and ALS

If you have been receiving SSDI for 24 months, you become may be able to access for Medicare at age 65 — the same as everyone else. However, you may have already been enrolled in Medicare before 65 through a different pathway. Check your current coverage to avoid duplicate enrollment.

If you have end-stage renal disease (ESRD) requiring dialysis or a kidney transplant, you can enroll in Medicare regardless of age. Enrollment is automatic once your treatment begins, and coverage starts the month your treatment starts. Similarly, if you have amyotrophic lateral sclerosis (ALS), you can enroll in Medicare when ready upon diagnosis, without waiting for age 65.

Frequently Asked Questions

Do I have to retire to enroll in Medicare at 65?

No. You can enroll in Medicare at 65 while still working. If your employer has 20 or more employees and covers you, your employer plan pays first and Medicare pays second. You can delay Part B enrollment without penalty as long as you have employer coverage, but you should still enroll in Part A.

What if I miss the enrollment window?

You can still enroll after the window closes, but you will pay a permanent penalty on your Part B and Part D premiums. The penalty is 10 percent of the Part B premium for each year you were may be able to access but not enrolled, and 1 percent of the national average Part D premium for each month. These penalties are permanent.

Will I be automatically enrolled if I am on Social Security?

Yes. If you are receiving Social Security retirement benefits, SSDI, or Railroad Retirement benefits before you turn 65, Medicare will automatically enroll you in Parts A and B. You will receive your Medicare card in the mail about two weeks before your birthday. You do not need to do anything.

Can I enroll in Medicare before age 65?

Only in specific cases: if you have been on SSDI for 24 months, if you have end-stage renal disease, or if you have ALS. Otherwise, you must wait until age 65. If you have one of these conditions, contact Medicare at 1-800-MEDICARE to learn about your enrollment options.

Do I need to enroll in Part D at the same time as Parts A and B?

No, but you should if you want prescription drug coverage. Part D has the same enrollment window as Parts A and B, and missing it results in a permanent penalty. You can enroll in Part D separately from Parts A and B, but do not delay — the important date is the same.

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.