The Basic Rule: Sign Up at 65, or Pay a Penalty for Life

You must sign up for Medicare during your Initial Enrollment Period, which runs for seven months: the three months before the month you turn 65, the month you turn 65, and the three months after. If you do not sign up during this window and you do not have other coverage that counts as "creditable coverage," you will pay a permanent penalty on top of your regular premiums for as long as you have Medicare.

The penalty is 10 percent of the standard Part B premium for each full year you went without coverage. If you waited five years, you pay 50 percent extra on top of the base premium, forever. The same rule applies to Part D (prescription drug coverage): miss the important date without creditable coverage, and you pay 1 percent of the national average Part D premium for each month you were uninsured, added to your premium for life.

The one exception is if you have health insurance through your job or your spouse's job. That coverage counts as creditable, and you can delay Medicare without penalty as long as you are still employed and covered. Once that employment ends or the coverage stops, you have eight months to sign up for Medicare before penalties kick in.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before you turn 65, the month of your birthday, and three months after.
  • If you miss this window and have no other health coverage, you will pay a permanent 10 percent penalty on Part B premiums and 1 percent per month on Part D premiums for the rest of your life.
  • If you have health insurance through work, you can delay Medicare without penalty, but you must sign up within eight months of losing that coverage.
  • Social Security will automatically sign you up for Medicare Part A and Part B at 65 if you are already receiving Social Security benefits.
  • You must actively sign up for Part D (prescription drugs) and Part C (Medicare Advantage) — they do not happen automatically.

What Happens If You Are Already on Social Security

If you are receiving Social Security retirement or disability benefits before you turn 65, Medicare will sign you up automatically. You will receive your Medicare card in the mail about three months before your 65th birthday. Part A (hospital insurance) and Part B (medical insurance) will start on the first day of the month you turn 65.

You do not need to do anything for Part A and Part B if you are already on Social Security. However, you still must sign up separately for Part D (prescription drug coverage) if you want it. If you do not sign up for Part D during your Initial Enrollment Period and you later need prescription coverage, you will face the 1 percent monthly penalty.

What Happens If You Are Not Yet on Social Security

If you are not receiving Social Security when you turn 65, 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. You have seven months to do it: three months before your birthday, the month of your birthday, and three months after.

Even if you plan to delay claiming Social Security benefits (to get a higher payment later), you should still sign up for Medicare at 65 if you do not have other coverage. Medicare and Social Security are separate programs. Delaying one does not delay the other, and missing the Medicare important date will cost you in penalties even if you never claim Social Security.

The Eight-Month Window After Losing Work Coverage

If you have health insurance through your job or your spouse's job, you do not have to sign up for Medicare at 65. You can stay on that coverage as long as you remain employed and the coverage continues. This is called creditable coverage, and it protects you from penalties.

Once your employment ends or your coverage stops, you have eight months to sign up for Medicare. This eight-month period is called your Special Enrollment Period. If you sign up within this window, you will not face penalties, even though you missed your Initial Enrollment Period. If you wait longer than eight months, penalties explore from the month your work coverage ended.

You must be able to prove you had creditable coverage. Keep your insurance cards, benefit statements, or letters from your employer showing the dates you were covered. When you sign up for Medicare, you may need to show this proof.

Part D and Part C Are Not Automatic

Part A and Part B will start automatically if you are on Social Security, or you can sign up for them during your Initial Enrollment Period. But Part D (prescription drug coverage) and Part C (Medicare Advantage plans) require you to sign up separately. They do not happen on their own.

If you do not sign up for Part D during your Initial Enrollment Period and you do not have other prescription drug coverage that counts as creditable, you will pay a penalty when you eventually join. The penalty is 1 percent of the national average Part D premium for each month you were without coverage. This penalty stays with you for life.

Part C (Medicare Advantage) does not carry a lifetime penalty if you miss the important date, but you can only join during certain times of year. If you miss your Initial Enrollment Period, you can join a Part C plan only during the Annual Enrollment Period (October 15 to December 7 each year) or if you may have access to for a Special Enrollment Period.

What Counts as Creditable Coverage

Creditable coverage means health insurance that is at least as good as Medicare. It includes employer health plans, union plans, TRICARE (military coverage), the Veterans Health Administration, and some state Medicaid programs. It does not include short-term health plans, discount cards, or coverage that only pays for specific services like dental or vision.

If you have creditable coverage through your job or your spouse's job, you can delay Medicare without penalty. If you have creditable coverage from another source — such as TRICARE or the VA — you may also be able to delay, but the rules vary. Contact Medicare at 1-800-MEDICARE to confirm whether your specific coverage counts.

How to Sign Up During Your Initial Enrollment Period

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. Online is usually fastest. You will need your Social Security number, birth date, and citizenship or immigration status.

For Part D and Part C, you sign up through Medicare.gov or by phone. You can compare plans side by side on the website. The enrollment period for Part D and Part C runs from October 15 to December 7 each year, but if you are turning 65, you can sign up during your seven-month Initial Enrollment Period instead.

Keep a record of when you sign up. Medicare will send you a confirmation letter. If you do not receive your Medicare card within three weeks of signing up, call 1-800-MEDICARE to check the status.

What Happens If You Miss Your important date

If you miss your Initial Enrollment Period and you do not have creditable coverage, you will owe a penalty. For Part B, the penalty is 10 percent of the standard premium for each full year you were uninsured. For Part D, it is 1 percent of the national average Part D premium for each month you were uninsured.

These penalties are permanent. Even if you sign up for Medicare later, the extra amount stays on your bill for life. The only way to avoid the penalty is to sign up during a Special Enrollment Period, which requires proof that you had creditable coverage or that you may have access to for another exception.

If you believe you have a valid reason for missing the important date — such as a language barrier, a serious illness, or incorrect information from Medicare — you can ask for a hearing. Contact Social Security or Medicare to request a review of your case.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before the month you turn 65. You can sign up as early as that point. Signing up early is a good idea because it gives you time to choose a plan and make sure everything is correct before your coverage starts.

What if I am still working at 65 and do not need Medicare yet?

If you have health insurance through your job, you can delay Medicare without penalty. Once you leave that job or lose the coverage, you have eight months to sign up. If you wait longer, you will owe penalties. Tell your employer's benefits office that you are delaying Medicare so they can document your creditable coverage.

Do I have to sign up for Part B if I only want Part A?

No. You can sign up for Part A (hospital insurance) alone and delay Part B (medical insurance) if you have other coverage. However, if you delay Part B without creditable coverage, you will owe a penalty when you eventually join. Part A does not carry a lifetime penalty for late sign-up.

What if I turned 65 years ago and never signed up for Medicare?

You can sign up now, but you will owe penalties for all the months you were uninsured. The penalty is calculated from the month after your Initial Enrollment Period ended. Contact Medicare at 1-800-MEDICARE to sign up and learn what your penalty will be.

Does my spouse have to sign up at the same time I do?

No. Each person has their own Initial Enrollment Period based on their own birthday. Your spouse signs up during the seven months around their 65th birthday, regardless of when you signed up. If your spouse has creditable coverage through their job, they can delay until that coverage ends.