You can enroll in Medicare Part A during specific windows, and missing them costs you money for life

Most people become may be able to access for Medicare Part A at 65, but the enrollment window that matters is the three months before your 65th birthday, the month you turn 65, and the three months after — a total of seven months called your Initial Enrollment Period. If you enroll during those seven months, your coverage starts on the first day of the month you turn 65. If you miss that window, you can still enroll later, but you will pay a permanent 10 percent penalty on your Part A premium for as long as you have Medicare, even if you do not need it for years.

The penalty applies only if you delayed enrollment without a valid reason. If you were still working and covered by your employer's health plan at 65, you have an eight-month window after you leave that job to enroll without penalty. If you did not have employer coverage and missed your Initial Enrollment Period, you can enroll during the General Enrollment Period (January 1 to March 31 each year), but the penalty still applies and your coverage does not start until July 1 of that year.

Key Takeaways

  • Your Initial Enrollment Period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
  • Enrolling during your Initial Enrollment Period means coverage starts on the first day of the month you turn 65, with no permanent penalty.
  • If you miss your Initial Enrollment Period and had no employer coverage, you pay a 10 percent penalty on Part A premiums for life and coverage starts July 1 of the year you enroll.
  • If you were covered by an employer plan at 65, you have eight months after leaving that job to enroll without penalty.
  • Part A covers hospital stays, skilled nursing facility care, hospice, and some home health services, so the penalty applies even if you do not use it when ready.

How the Initial Enrollment Period works

The Initial Enrollment Period is a seven-month window centered on your 65th birthday. It begins three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your Initial Enrollment Period runs from March through September. You can enroll in person, by phone, by mail, or online through Medicare.gov.

The month you enroll determines when your coverage starts. If you enroll in the three months before your birthday, coverage starts on the first day of the month you turn 65. If you enroll in the month of your birthday or the three months after, coverage starts on the first day of the month after you enroll. This timing matters if you have a planned hospital stay or surgery — enrolling early in your Initial Enrollment Period ensures coverage is active before you need it.

What happens if you miss the Initial Enrollment Period

If you do not enroll during your Initial Enrollment Period and you were not covered by an employer health plan at age 65, you can enroll during the General Enrollment Period, which runs January 1 to March 31 each year. However, your coverage will not start until July 1 of that year, leaving you uninsured for months. More importantly, you will owe a permanent 10 percent penalty on your Part A premium for every year you have Medicare.

The penalty is calculated on the standard Part A premium amount, which changes each year. Even if you do not use Part A when ready — for example, if you stay healthy and do not need hospitalization — you still pay the penalty if you eventually enroll. The only way to avoid the penalty is to have had continuous creditable coverage (such as an employer plan or TRICARE) from age 65 until you enroll.

Employer coverage and the eight-month grace period

If you were covered by a health plan through your own job (or your spouse's job) at age 65, you do not have to enroll in Part A at 65. Instead, you have an eight-month window after you or your spouse leaves that job to enroll without penalty. This grace period is separate from your Initial Enrollment Period and gives you time to transition to Medicare after employment ends.

To use this grace period, you must have had employer coverage based on current employment — coverage from a former employer or COBRA does not count. When you do enroll, bring documentation of your employment and the date you left the job. Medicare will verify your employer coverage and waive the penalty if you meet the requirements.

Part A costs and what the penalty covers

Most people do not pay a monthly premium for Part A if they or their spouse paid Medicare taxes for at least 10 years while working. However, if you do not meet that requirement, you pay a monthly premium that varies by year. In 2024, the standard Part A premium is $505 per month for those with fewer than 30 quarters of Medicare tax history, and $278 per month for those with 30 to 39 quarters.

The 10 percent penalty applies to whichever premium you would normally pay. If you delayed enrollment without a valid reason, you pay an extra 10 percent on top of your regular premium for as long as you have Part A. This is a permanent penalty — it does not go away after a certain number of years, and it applies whether you use Part A or not.

Special situations that extend your enrollment window

Certain life events give you a Special Enrollment Period outside your Initial Enrollment Period. These include losing employer coverage, moving out of your plan's service area, or experiencing a may have access to life event. If you lose employer coverage, you have two months from the date coverage ends to enroll in Part A without penalty.

If you are a federal employee, railroad retiree, or covered under TRICARE (military health coverage), your enrollment rules may differ. Federal employees and railroad retirees have their own enrollment periods tied to their retirement dates. TRICARE beneficiaries can delay Part A enrollment without penalty while TRICARE coverage is active. Check with your specific plan administrator if you fall into one of these categories.

How to enroll and what documents you need

You can enroll in Part A through Medicare.gov, by calling 1-800-MEDICARE, by visiting your local Social Security office, or by mail. You will need your Social Security number and proof of citizenship or legal residency. If you are enrolling based on an employer grace period, have your employment end date and employer name ready.

Enrollment is free, and there is no process fee. Once you enroll, Medicare sends you a Medicare card in the mail within two weeks. Your coverage starts on the date Medicare confirms, which depends on when you enroll within your enrollment period. Keep your Medicare card in a safe place and bring it to all medical appointments.

Frequently Asked Questions

What if I turn 65 and I am still working?

If you are still working and covered by your employer's health plan, you do not have to enroll in Part A at 65. You can wait until you leave your job, then enroll within eight months without penalty. However, if you want to enroll at 65 anyway, you can — there is no rule against it.

Can I enroll in Part A without enrolling in Part B?

Yes. Part A and Part B have separate enrollment periods and separate penalties. You can enroll in Part A without Part B, though most people enroll in both. If you delay Part B without a valid reason, you pay a different penalty on Part B premiums.

What if I was not working and did not pay Medicare taxes?

You may still be may be able to access for Part A at 65 based on your spouse's work history, or you may be able to purchase Part A if you do not meet the free may be able to access requirement. Contact Social Security or Medicare to find out whether you may have access to and what your premium would be.

Does the Part A penalty ever go away?

No. The 10 percent penalty is permanent and applies for every month you have Part A coverage. It does not expire after a certain number of years or reset if you stop using Medicare temporarily.

What if I missed my Initial Enrollment Period by a few days?

If you missed your seven-month window, you cannot enroll until the next General Enrollment Period (January 1 to March 31). You will owe the permanent penalty unless you had continuous employer coverage or another may have access to reason for the delay. Contact Medicare to discuss your specific situation.