You must sign up for Medicare at 65, even if you are still working

Medicare enrollment is not optional at 65. You are required to sign up during 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. If you miss this window, you will pay a permanent penalty on your premiums for as long as you have Medicare.

The penalty applies even if you do not use Medicare right away. If you are covered by an employer health plan and delay signing up, you will still owe the penalty unless your employer has 20 or more employees. The only exception is if you are still actively working and covered by your employer's plan — in that case, you can delay Part B enrollment without penalty, but you must sign up for Part A (hospital insurance) at 65.

The enrollment important date is strict. Missing it by even one day means the penalty starts. You cannot get it waived later, and it compounds every year you remain enrolled in Medicare.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after.
  • Part A (hospital insurance) is required at 65 unless you are still working and covered by an employer plan with 20 or more employees.
  • Part B (medical insurance) can be delayed without penalty only if you have employer coverage and are actively working.
  • Missing your enrollment important date triggers a permanent 10 percent penalty on Part B premiums and a 1 percent penalty per month for Part D (prescription drug coverage).
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Part A enrollment is automatic if you receive Social Security

If you are already collecting Social Security retirement benefits when you turn 65, Medicare Part A is enrolled automatically. You do not have to do anything. Social Security will send you a Medicare card in the mail about three months before your 65th birthday.

If you are not yet collecting Social Security, you must sign up for Part A yourself during your Initial Enrollment Period. You can do this online at Medicare.gov, by calling 1-800-MEDICARE, or by visiting your local Social Security office. Part A covers hospital stays, skilled nursing facility care, hospice, and home health services.

Part B has a important date unless you have employer coverage

Part B (medical insurance covering doctor visits and outpatient care) must be enrolled in during your Initial Enrollment Period unless you have employer health coverage and are still actively working. If you have employer coverage, you can delay Part B without penalty, but you must enroll within eight months of losing that coverage or retiring — whichever comes first.

If you miss the important date and do not have employer coverage, you pay a 10 percent premium penalty for each full year you were not enrolled. This penalty is permanent and stays on your account for life. For example, if you turn 65 in January 2024 and do not sign up for Part B until January 2026, you owe a 20 percent penalty on top of your regular Part B premium.

The exception is narrow: you must be actively working, your employer must have 20 or more employees, and you must be covered by that employer's health plan. Retiree health plans do not count. If you are unsure whether your coverage qualifies, contact your employer's benefits department or call 1-800-MEDICARE.

Part D (prescription drug coverage) has its own important date

Part D enrollment is not required, but if you go without it and later sign up, you pay a 1 percent penalty per month for every month you were not enrolled. Unlike Part B, this penalty is not permanent — it ends when you drop the coverage — but it can add up quickly.

You can enroll in Part D during your Initial Enrollment Period or during the annual Open Enrollment Period (October 15 to December 7 each year). If you have employer or union retiree coverage that includes prescription drugs, you may be able to delay Part D without penalty, but you must have written proof that your coverage is at least as good as Medicare's. Ask your employer for a notice of creditable coverage before you turn 65.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your seven-month window, you enter a General Enrollment Period that runs January 1 to March 31 each year. You can sign up then, but the penalties explore when ready. Part B premiums increase by 10 percent for each full year you were not enrolled, and Part D premiums increase by 1 percent per month.

These penalties are permanent. You cannot appeal them or have them removed. If you delayed Part B by three years, you will pay a 30 percent penalty on your Part B premium for the rest of your life. The only way to avoid the penalty is to sign up during your Initial Enrollment Period or to have employer coverage that qualifies for a delay.

If you are already on Medicare and missed the important date, you can still enroll during the General Enrollment Period, but the penalty will be calculated and applied to your account. There is no way to go back and erase it.

Special circumstances that extend your enrollment period

A few situations give you extra time to sign up without penalty. If you are a U.S. citizen or permanent resident living outside the United States, your Initial Enrollment Period is extended by the time you are abroad. If you are a federal employee, you may have different rules depending on your health plan.

If you are receiving disability benefits from Social Security or Railroad Retirement Board, you are automatically enrolled in Medicare Part A and Part B after 24 months of receiving benefits. You do not have to sign up yourself. If you are on end-stage renal disease (ESRD) dialysis or have had a kidney transplant, you may have different enrollment rules — contact Medicare directly to understand your situation.

If you missed your important date because of a mistake by Social Security or Medicare, you can request a hearing to have the penalty waived, but this is rare and requires documentation that the government made the error.

How to sign up during your Initial Enrollment Period

You have three ways to enroll. Online at Medicare.gov is the fastest: create an account, answer the questions about your coverage, and submit. You will see confirmation when ready. By phone, call 1-800-MEDICARE (1-800-633-4227) and speak to a representative who can walk you through the process. In person, visit your local Social Security office with your Social Security card and proof of citizenship or permanent residency.

If you are signing up for Part B and have employer coverage, bring a letter from your employer stating the number of employees and confirming you are actively working. This protects you from penalties if you delay Part B. If you are signing up for Part D, have a list of your current medications ready so you can compare plans and choose one that covers them at the lowest cost.

Enrollment usually takes effect the first day of the month after you sign up, but if you sign up during the first three days of your birth month, coverage can start that same month. Plan ahead so your coverage does not lapse.

Frequently Asked Questions

Can I delay Medicare if I am still working?

You can delay Part B without penalty if you are actively working and covered by an employer health plan with 20 or more employees. You must still sign up for Part A at 65. Once you retire or lose employer coverage, you have eight months to sign up for Part B without penalty. After that, the 10 percent penalty applies.

What if I turn 65 and do not know when my Initial Enrollment Period ends?

Your Initial Enrollment Period is always seven months: three months before your birth month, your birth month, and three months after. If you turn 65 in June, your period runs March through September. Call 1-800-MEDICARE if you are unsure of your exact dates.

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

Part A and Part B are required at 65 (with limited exceptions for active workers). Part D is optional but carries a penalty if you skip it and enroll later. Part C (Medicare Advantage) is optional and replaces Part A and B if you choose it. You do not have to take all of them, but missing important date costs money.

What is the penalty if I miss the important date?

Part B premiums increase by 10 percent for each full year you were not enrolled. Part D premiums increase by 1 percent per month. These penalties are permanent for Part B and explore for as long as you have Medicare. Part D penalties end if you drop the coverage.

Can I sign up for Medicare before I turn 65?

Yes. Your Initial Enrollment Period begins three months before your birth month. You can sign up as early as that date. Signing up early ensures your coverage starts on time and you do not accidentally miss the important date.