When You Must File for Medicare: Deadlines and Penalties

You must file for Medicare within three months before or after your 65th birthday, or face a permanent penalty on your premiums

Medicare enrollment is not automatic. You have a seven-month window centered on your 65th birthday — three months before, your birth month, and three months after — to sign up for Part A and Part B without penalty. If you miss this window and do not have other health coverage, you will pay a higher premium for Part B for as long as you have Medicare. Part A (hospital insurance) rarely carries a penalty because most people are covered through work or a spouse's work history, but Part B (medical insurance) penalties are permanent and calculated as 10 percent of the standard premium for each full year you were not enrolled.

The exact important date depends on your birth month. If you were born in March, your initial enrollment period runs from December through June. If you were born in November, it runs from August through February. The Social Security Administration processes enrollments submitted during this window with no penalty, even if you submit in the final month.

Key Takeaways

Your initial enrollment period is seven months long: three months before your 65th birthday, your birth month, and three months after.
Missing this window triggers a permanent 10 percent premium penalty on Part B for each year you delayed, even if you enroll later.
You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
If you have employer health coverage or are still working, you may have a different important date and should contact your employer's benefits office before your 65th birthday.
Part A has no premium penalty for most people, but Part B penalties are permanent once applied.

What happens if you miss your initial enrollment period

If you do not enroll during your seven-month window, you enter a general enrollment period that runs January 1 through March 31 each year. However, coverage does not start until July 1 of that year, creating a gap. More importantly, you will owe the Part B penalty retroactively — it applies to every month from when you first became may be able to access until you actually enroll.

The penalty is permanent. If you were may be able to access at 65 but did not enroll until age 68, you owe 30 percent more on your Part B premium (10 percent for each of the three years you were late) for the rest of your life. There is no way to remove this penalty once it is applied, even if you later drop coverage and re-enroll.

Part A penalties are less common because most people have 40 quarters of work history and pay no premium at all. But if you do owe a Part A premium and miss enrollment, you face a 10 percent penalty per year, the same as Part B.

Who has a different important date

If you are still working and your employer has 20 or more employees, you are not required to enroll in Medicare Part B when you turn 65. You can delay enrollment without penalty as long as you are covered under your employer's plan. This is called creditable coverage. You have eight months after you leave your job or your coverage ends to enroll in Part B without penalty — this is your Special Enrollment Period.

If your employer has fewer than 20 employees, Medicare becomes your primary payer at 65, and you should enroll during your initial enrollment period even if you have employer coverage. Your employer's plan will be secondary.

If you receive disability benefits from Social Security or Railroad Retirement Board, you are automatically enrolled in Medicare Part A and Part B at age 65. You do not need to take action, but you should review your enrollment to make sure it is correct. If you want to decline Part B, you must do so in writing within your initial enrollment period.

How to enroll and what you need

You can enroll online at Medicare.gov without leaving your home. You will need your Social Security number, date of birth, and citizenship or immigration status. The online process takes about 10 minutes and you receive confirmation when ready.

You can also call 1-800-MEDICARE (1-800-633-4227) and speak to a representative. They can enroll you over the phone and answer questions about your specific situation. The line is open Monday through Friday, 8 a.m. to 8 p.m. Eastern time, and Saturday 9 a.m. to 1 p.m. Eastern time.

If you prefer in-person help, visit your local Social Security office. Bring your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residency (utility bill or lease). You do not need an appointment, but wait times vary by location.

Timing your enrollment if you are still working

If you plan to keep working past 65, contact your employer's benefits office at least three months before your 65th birthday. Ask whether your employer offers retiree health coverage and whether you must enroll in Medicare at 65 or can delay. Ask specifically whether your plan is creditable coverage — this determines whether you can delay Part B without penalty.

If your employer confirms you have creditable coverage, you can wait to enroll in Medicare until you actually retire or your coverage ends. Write down the date your coverage ends and set a reminder to enroll within eight months. If you miss that eight-month window, the Part B penalty applies.

If your employer does not offer retiree coverage or your coverage ends before you retire, enroll in Medicare during your initial enrollment period even if you are still working. You can have both employer coverage and Medicare at the same time.

Special situations and exceptions

If you are not yet 65 but receive Social Security disability benefits, you become may be able to access for Medicare automatically after 24 months of receiving disability payments. You do not need to enroll — it happens automatically. You should receive a Medicare card in the mail about three months before your may be able to access date.

If you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS), you may be may be able to access for Medicare before 65. Contact Social Security to confirm your may be able to access date and enroll during your seven-month initial enrollment period centered on that date.

If you are a federal employee, railroad retiree, or have other special employment status, your enrollment rules may differ. Contact your agency's benefits office or the Railroad Retirement Board directly — do not rely on the standard Medicare timeline.

What to do if you think you missed your important date

If you believe you missed your initial enrollment period, contact Social Security or Medicare when ready. In rare cases, you may be able to request a Special Enrollment Period if you can show that Social Security or Medicare gave you incorrect information, or if you had a may have access to life event like losing employer coverage.

Do not assume the penalty applies automatically. Some people who miss the important date can still enroll without penalty if they meet specific conditions. A representative can review your situation and tell you whether you may have access to for an exception. Call 1-800-MEDICARE or visit your local Social Security office with documentation of when your coverage ended or when you became aware of the important date.

Frequently Asked Questions

Can I enroll in Medicare before my 65th birthday?

Yes. Your initial enrollment period starts three months before your 65th birthday, so you can enroll as early as three months in advance. This is actually recommended because it gives Medicare time to process your enrollment and send your card before your birthday.

What if I turn 65 in the middle of the month?

Your birth month counts as one full month in your seven-month window, regardless of the date. If you were born on March 15, your enrollment period runs from December 1 through June 30. You can enroll on any day during this window.

Do I have to enroll in Part B if I only want Part A?

No. You can enroll in Part A alone and delay Part B if you have other coverage. However, if you delay Part B without creditable coverage, you will owe the 10 percent penalty per year when you eventually enroll. If you have creditable coverage, you can delay Part B without penalty.

What if I was working and did not know I had to enroll?

Contact Social Security or Medicare when ready with documentation of your employment and coverage dates. If you can show that you had creditable employer coverage, you may not owe a penalty even if you missed your initial enrollment period. A representative can review your specific circumstances.

Can the penalty ever be removed?

No. Once the Part B penalty is calculated and applied, it is permanent. It does not go away if you drop coverage and re-enroll later. This is why it is critical to enroll during your initial enrollment period or confirm that you have creditable coverage that allows you to delay without penalty.

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.