You must enroll in Medicare during your Initial Enrollment Period, which starts three months before the month you turn 65 and ends three months after

Your Initial Enrollment Period is a seven-month window centered on your 65th birthday month. If you turn 65 in June, your period runs from March through September. During this window, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance) without penalty.

If you miss this window, you will pay a permanent penalty on your Part B and Part D (prescription drug) premiums for as long as you have Medicare. The penalty is 10 percent of the Part B premium for each full 12 months you were may be able to access but not enrolled. Part D penalties work the same way. These penalties do not go away, even if you enroll years later.

There are a few situations where you can enroll outside your Initial Enrollment Period without penalty. If you were still working and covered by your employer's health plan when you turned 65, you have eight months after that coverage ends to enroll without penalty. If you are a federal employee, railroad retiree, or covered by TRICARE (military health coverage), different rules explore — ask your benefits office about your specific enrollment window.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before your 65th birthday month, the month itself, and three months after.
  • Enrolling late in Part B or Part D means you pay a permanent 10 percent penalty on your premium for every 12 months you delayed.
  • If you are still working and covered by employer health insurance at 65, you have eight months after that coverage ends to enroll without penalty.
  • You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

What happens if you enroll after your Initial Enrollment Period ends

If you miss your Initial Enrollment Period and do not have employer coverage or another may have access to reason, you will have to wait until the next General Enrollment Period to sign up. General Enrollment runs January 1 through March 31 each year, and coverage starts July 1. This means if you miss your Initial Enrollment Period in September and do not enroll during General Enrollment, you will go without Medicare coverage for months.

The late enrollment penalty applies even if you enroll during General Enrollment. You will pay it for the rest of your life. For example, if you were supposed to enroll in Part B at 65 but did not enroll until age 68, you owe a 30 percent penalty (10 percent for each year you were late) on top of your regular Part B premium every month going forward.

When you do not have to enroll at 65

You can delay enrolling in Part A without penalty if you are still working and your employer has 20 or more employees. You can delay Part B under the same condition. Once you or your spouse stops working, or your employer coverage ends, you have eight months to enroll without penalty.

If you are receiving Social Security benefits when you turn 65, you are enrolled in Part A and Part B automatically. You do not have to do anything. Your Medicare card will arrive in the mail about two weeks before your 65th birthday. If you do not want Part B, you must decline it in writing before it starts.

If you are not yet receiving Social Security, you must enroll yourself during your Initial Enrollment Period, even if you plan to delay Social Security. Delaying Social Security does not delay your Medicare enrollment requirement.

How to enroll during your Initial Enrollment Period

You can enroll online at Medicare.gov using your Social Security number and basic personal information. The online process takes about 10 minutes. You do not need to upload documents or wait for a response — your enrollment is confirmed when ready.

You can also call 1-800-MEDICARE (1-800-633-4227) to enroll by phone. Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time. Have your Social Security number and information about any current health coverage ready when you call.

A third option is to visit your local Social Security office in person. You can find the nearest office at ssa.gov or by calling 1-800-772-1213. Bring your Social Security card, proof of citizenship or legal residency, and proof of age. If you are enrolling in Part B, bring proof of your current address as well.

Special situations that change your enrollment important date

If you are a federal employee or retiree, your enrollment rules are different. Federal employees can enroll in Medicare while still working without losing their federal employee health benefits. Contact your agency's benefits office for your specific enrollment window.

If you are covered by TRICARE (military health insurance), you can keep TRICARE and delay Medicare Part B without penalty as long as you are covered by TRICARE. Once TRICARE coverage ends, you have eight months to enroll in Part B without penalty. Contact your TRICARE regional office to confirm your enrollment important date.

If you are a railroad retiree covered by the Railroad Retirement Board, your enrollment rules also differ. Contact the Railroad Retirement Board at 1-877-772-5772 to learn when you must enroll.

What to do if you missed your enrollment important date

If you missed your Initial Enrollment Period and do not have employer coverage or another may have access to reason, you can still enroll during General Enrollment (January 1 through March 31). Coverage will start July 1, and you will pay the late enrollment penalty.

If you believe you have a may have access to reason to enroll outside General Enrollment without penalty, you can request a Special Enrollment Period. may have access to reasons include losing employer coverage, moving out of your plan's service area, or having Medicare incorrectly terminate your coverage. You must request a Special Enrollment Period within 63 days of the event that qualifies you. Contact Medicare at 1-800-MEDICARE to request one.

Do not delay if you think you may have access to for a Special Enrollment Period. The 63-day window is strict, and missing it means waiting until the next General Enrollment Period.

Questions to ask your doctor or benefits counselor

Before your 65th birthday, ask your current doctor whether they accept Medicare. Some doctors do not, and you may need to find a new one. Ask your employer's benefits office whether you will still be covered after you turn 65, and if so, for how long. This determines whether you can delay Medicare without penalty.

If you take prescription medications, ask your pharmacist which Medicare Part D plans cover them. Costs vary widely between plans, and choosing the wrong one can be expensive. If you are unsure about your enrollment important date, contact your State Health Insurance information Program (SHIP). SHIP offers free counseling about Medicare enrollment and can answer questions specific to your situation. Find your state's SHIP at shiptalk.org or by calling 1-877-839-2675.

Frequently Asked Questions

What if I turn 65 while still working?

If your employer has 20 or more employees and you are covered by their health plan, you can delay enrolling in Part A and Part B without penalty. Once you stop working or your coverage ends, you have eight months to enroll without penalty. If your employer has fewer than 20 employees, you must enroll in Part A and Part B when you turn 65.

Can I enroll in just Part A and skip Part B?

Yes. Part A (hospital insurance) has no monthly premium if you or your spouse paid Medicare taxes for at least 10 years. You can enroll in Part A alone during your Initial Enrollment Period. However, if you do not enroll in Part B when you are first may be able to access, you will pay a late enrollment penalty if you enroll later, unless you have a may have access to reason.

What if I miss the important date by a few days?

Your Initial Enrollment Period is seven months long, so a few days late means you have missed it. You cannot enroll until the next General Enrollment Period (January 1 through March 31), and you will owe the late enrollment penalty. If you believe you have a may have access to reason for a Special Enrollment Period, contact Medicare when ready at 1-800-MEDICARE.

Do I have to enroll in Part D when I turn 65?

Part D (prescription drug coverage) is optional. However, if you do not enroll when you are first may be able to access and later want it, you will pay a late enrollment penalty. The penalty is 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled. If you do not take prescription medications, you can skip Part D without penalty.

What happens if I enroll late but then move to a different state?

The late enrollment penalty follows you. It does not change based on where you live. If you move, make sure to update your address with Medicare so your bills and notices reach you. Call 1-800-MEDICARE or visit Medicare.gov to update your information.