You have specific windows to enroll in Medicare, and missing them costs you money for life

Medicare enrollment is not open year-round. You have a seven-month Initial Enrollment Period centered on your 65th birthday — three months before, the month you turn 65, and three months after. If you miss this window, you pay a permanent penalty on your premiums unless you have a valid reason for the delay.

The penalty is not a one-time fee. It is a percentage added to your Part B and Part D premiums every month you are enrolled, for as long as you have Medicare. For every 12 months you delay Part B past age 65, you pay an extra 10 percent. For every 12 months you delay Part D (prescription drug coverage), you pay an extra 1 percent per month. These penalties stack and do not go away.

If you are still working at 65 and covered by your employer's health plan, you may be able to delay without penalty — but you have to tell Medicare that you have group coverage, and the rules are strict. This section explains when you must enroll, what happens if you do not, and which situations let you enroll late without paying extra.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before your 65th birthday, the month you turn 65, and three months after.
  • If you miss this window, you pay a permanent 10 percent penalty on Part B premiums and 1 percent per month on Part D premiums for every 12 months you delay.
  • If you are still working and covered by your employer's health plan at 65, you can delay Part B and Part D without penalty, but you must notify Social Security in writing.
  • You get a second chance to enroll without penalty during General Enrollment Period (January 1 to March 31 each year), but the penalty still applies unless you have employer coverage.
  • Special Enrollment Periods allow penalty-free enrollment if you lose employer coverage, move out of your plan's service area, or experience other may have access to events.

Your Initial Enrollment Period: The seven-month window

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. If you turn 65 in June, your window opens in March and closes in September. During these seven months, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance) without penalty, and you can also enroll in a Part D plan (prescription drug coverage) or a Medicare Advantage plan that includes drug coverage.

You do not have to enroll on your birthday. You can enroll at any point during the seven months. However, your coverage start date depends on when you enroll. If you enroll in the month you turn 65 or earlier, coverage starts on the first day of the month you turn 65. If you enroll after your birthday month, coverage starts the first day of the month after you enroll. This timing matters if you have a gap in health coverage or take medications you need to fill right away.

Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years. Most people should enroll in Part A during their Initial Enrollment Period even if they are still working, because there is no premium and no penalty for enrolling early. Part B (medical insurance) has a monthly premium, and this is where the penalty applies if you delay.

What happens if you miss your Initial Enrollment Period

If you do not enroll during your seven-month window and you do not have a valid reason for the delay, you will pay a penalty for the rest of your life on Medicare. The Part B penalty is 10 percent of the standard premium for every 12 months you were may be able to access but not enrolled. If the standard Part B premium is $165 per month and you delay two years, you pay an extra $33 per month forever.

The Part D penalty works differently. It is 1 percent of the national average premium for every month you delay, rounded to the nearest dollar. In 2024, that is roughly $4.50 per month for every month you delay. If you delay two years (24 months), you pay about $108 extra per year on your Part D premium for life. These penalties do not expire and do not decrease over time.

The only way to avoid these penalties after you miss your Initial Enrollment Period is to have a may have access to life event that opens a Special Enrollment Period. Losing employer coverage, moving out of your plan's service area, or having a family member die are examples. If you do not have a may have access to event, you can only enroll during General Enrollment Period (January 1 to March 31 each year), and the penalty will still explore.

Staying on employer coverage past 65: How to delay without penalty

If you are still working at 65 and your employer offers health insurance, you may be able to delay Medicare Part B and Part D without paying a penalty. This is called creditable coverage. Your employer plan must be based on current employment (not retiree coverage), and you must have it through your employer or your spouse's employer. Coverage through COBRA, the ACA marketplace, or Medicaid does not count as creditable coverage for this purpose.

To delay without penalty, you must tell Social Security in writing that you have group health coverage through your employer. You cannot straightforward assume they know. Contact your local Social Security office or call 1-800-772-1213 and ask how to report your employer coverage. Social Security will send you a form to complete. Keep a copy of this form and any confirmation Social Security sends you — you will need it later to prove you had a valid reason to delay.

Once you leave your job or lose your employer coverage, you have eight months to enroll in Medicare Part B without penalty. This eight-month window is your Special Enrollment Period. You must enroll within this time frame and provide proof that you had employer coverage. If you wait longer than eight months after leaving your job, the penalty applies.

General Enrollment Period: A second chance with a catch

If you miss your Initial Enrollment Period and do not have employer coverage or a may have access to life event, you can still enroll during General Enrollment Period, which runs January 1 to March 31 every year. Your coverage will start July 1 of that year. This means if you enroll in March, you have a gap from April through June with no Medicare coverage.

The catch is that the penalty still applies. You will pay the 10 percent Part B penalty and the 1 percent per month Part D penalty for every 12 months you delayed, even though you are enrolling during General Enrollment Period. General Enrollment Period is a safety net, not a penalty-free option. It exists so you do not go without coverage forever, but it does not erase the cost of missing your Initial Enrollment Period.

You can use General Enrollment Period every year if you need to make changes, but penalties only explore once for the initial delay. After you enroll, you can make changes during the annual Open Enrollment Period (October 15 to December 7) without additional penalties.

Special Enrollment Periods: may have access to events that waive penalties

A Special Enrollment Period is a window outside the normal enrollment times that lets you enroll in Medicare without penalty if you experience a may have access to event. The most common may have access to event is losing employer-based health coverage. Other events include moving out of your plan's service area, having a family member die, getting divorced, or having a change in your Medicaid status.

If you lose employer coverage, you have eight months from the date coverage ends to enroll in Medicare Part B without penalty. You must enroll within this window and provide proof of the coverage you had. Proof can be a letter from your employer, a final pay stub showing health insurance deductions, or a COBRA notice. Social Security will ask for this documentation.

If you move out of your current Medicare plan's service area, you can enroll in a new plan during your Special Enrollment Period. If you are on Original Medicare (Part A and Part B) and move, you can enroll in a Medicare Advantage plan or a Medigap plan without waiting for Open Enrollment. The timing and rules vary by situation, so contact Medicare at 1-800-MEDICARE to confirm your specific event qualifies.

How to enroll: Where to go and what to bring

You can enroll in Medicare through three main routes: Social Security, Medicare.gov, or your local Social Security office. If you are already receiving Social Security benefits, you will be enrolled in Part A and Part B automatically three months before your 65th birthday. You do not have to do anything. If you are not yet receiving Social Security, you must enroll yourself.

To enroll online, go to Medicare.gov and click "Enroll in Medicare." You will need your Social Security number, birth date, and citizenship or immigration status. The process takes about 10 minutes. You can also call Social Security at 1-800-772-1213 (TTY 1-800-325-0778) to enroll by phone, or visit your local Social Security office in person.

For Part D (prescription drug coverage) and Medicare Advantage plans, you enroll separately through Medicare.gov or by calling 1-800-MEDICARE. You will need a list of your current medications to compare Part D plans, because premiums and coverage vary widely. If you are enrolling in a Medicare Advantage plan, that plan usually includes Part D, so you do not enroll separately.

Questions to ask your doctor and Social Security

Before your 65th birthday, ask your doctor whether you should enroll in Original Medicare (Part A and Part B) or a Medicare Advantage plan. Ask which prescription drugs you take are covered under different Part D plans, and whether your doctor is in-network for the plans you are considering. Ask whether you need supplemental coverage (Medigap) to cover costs Original Medicare does not pay.

If you are still working at 65, ask your employer's benefits department whether your health plan is considered creditable coverage for Medicare purposes. Ask them to provide written confirmation. Then contact Social Security and report your employer coverage in writing before you turn 65, if possible. Ask Social Security to send you written confirmation that they have recorded your employer coverage.

If you have a life event like losing a job or moving, ask Social Security whether it qualifies for a Special Enrollment Period. Ask what documents you need to provide as proof. Do not assume your situation qualifies — ask first, and get the answer in writing.

When to seek help from Medicare or Social Security

Contact Medicare at 1-800-MEDICARE if you are within three months of your 65th birthday and have not yet enrolled, if you are unsure whether you need Part D, or if you want to compare Medicare Advantage and Medigap plans. Medicare counselors can walk you through your options and help you understand the costs of each plan. This service is free.

Contact Social Security at 1-800-772-1213 if you are not yet receiving Social Security benefits and want to enroll in Medicare, if you need to report employer coverage, or if you think you may have missed your enrollment important date and want to know whether you may have access to for a Special Enrollment Period. Social Security handles Part A and Part B enrollment.

If you have already missed your Initial Enrollment Period and are facing a penalty, contact Social Security to ask whether you have a valid reason for the delay that might waive the penalty. The rules are strict, but some situations do may have access to. It is worth asking before you accept the penalty as permanent.

Frequently Asked Questions

What if I turn 65 while still working full-time?

You can delay Part B and Part D without penalty if your employer offers health coverage based on your current employment. You must notify Social Security in writing that you have employer coverage. Part A (hospital insurance) is usually free, so most people enroll in Part A even while working. Once you leave your job, you have eight months to enroll in Part B and Part D without penalty.

Can I enroll in Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before your 65th birthday. You can enroll as early as three months before. If you enroll before your birthday month, coverage starts the first day of the month you turn 65. This is useful if you want to make sure coverage is in place on your birthday.

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

Missing the important date by even one day means you have missed your Initial Enrollment Period. The penalty applies unless you have a may have access to life event or employer coverage. There is no grace period. If you realize you are close to the important date, enroll when ready. If you have already missed it, contact Social Security right away to ask whether your situation qualifies for a Special Enrollment Period.

Do I have to enroll in Part D if I do not take any medications?

You are not required to enroll in Part D if you do not take medications. However, if you enroll later when you do need prescriptions, you will pay a penalty for every month you delayed. If there is any chance you might need prescriptions in the future, enrolling during your Initial Enrollment Period protects you from the penalty. The monthly premium for Part D varies, but it is usually less than the penalty you would pay for delaying.

What if I was not told about Medicare and missed my important date?

Not being told about Medicare does not waive the penalty. However, if you can show that Social Security or Medicare gave you incorrect information in writing, you may be able to appeal the penalty. Contact Social Security and ask about filing an appeal. Bring any written communication you received that led you to believe you did not need to enroll.