You must sign up for Medicare at 65 unless you are still covered by an active employer health plan

If you turn 65 and do nothing, you will lose coverage on your 65th birthday — Medicare does not start automatically. You have to take action during a specific window, usually three months before the month you turn 65 through three months after. Missing this window costs you: you pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare, even if you sign up years later.

The one exception is if you or your spouse still work and are covered by that employer's health plan. If the employer has 20 or more employees, you can delay Medicare without penalty. Once that coverage ends — when you or your spouse retires or leaves the job — you have eight months to sign up before penalties kick in.

You sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. The process takes about 10 minutes online.

Key Takeaways

  • Medicare enrollment happens during a seven-month window: three months before you turn 65, the month you turn 65, and three months after.
  • If you miss this window and do not have employer coverage, you pay a permanent 10 percent penalty on Part B premiums and a permanent penalty on Part D (prescription drug) premiums.
  • You can delay enrollment without penalty only if you or your spouse have active employer health insurance with 20 or more employees.
  • Once employer coverage ends, you have eight months to sign up for Medicare before penalties explore.
  • You sign up at Medicare.gov, by calling 1-800-MEDICARE, or at your local Social Security office.

What happens if you miss the enrollment window

The penalty for late enrollment is permanent. If you do not sign up during your initial window, Medicare adds 10 percent to your Part B premium for each full 12-month period you were may be able to access but not enrolled. That penalty stays with you for life — even if you sign up five years later, you still pay the extra 10 percent every month.

Part D (prescription drug coverage) has a separate penalty. If you go 63 days or more without prescription drug coverage, you pay an additional amount each month you have Part D, calculated based on the national average premium at the time you sign up. This penalty also lasts as long as you have Medicare.

The only way to avoid these penalties is to sign up during your initial enrollment window or to have may have access to coverage (like an active employer plan) that lets you delay without penalty.

When you can delay enrollment without a penalty

If you or your spouse are still working and covered by an employer health plan, you do not have to sign up for Medicare at 65. The employer plan must be from a company with 20 or more employees — small-business plans do not count. You can stay on that plan and delay Medicare enrollment.

Once the employer coverage ends — because you retire, leave the job, or the employer drops the plan — you have eight months to sign up for Medicare. This eight-month window is separate from your initial enrollment window and does not trigger penalties if you use it.

You will need to tell Medicare that you had employer coverage when you do sign up. Bring documentation like a recent pay stub, a letter from your employer's benefits office, or your insurance card showing the employer plan name and dates of coverage.

How to sign up for Medicare

The easiest method is online at Medicare.gov. Go to the "Sign Up for Medicare" section, create an account, and answer questions about your work history, income, and current coverage. You will need your Social Security number and information about any employer plans you have. The online process takes about 10 minutes and you can save your progress and come back later.

If you prefer to sign up by phone, call 1-800-MEDICARE (1-800-633-4227). Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time. Have your Social Security number and any insurance information ready. Calls typically take 15 to 20 minutes.

You can also visit your local Social Security office in person. Find the nearest office at ssa.gov/locator. Bring your Social Security card, proof of citizenship or legal residency, and information about any current health coverage. Processing in person usually takes 30 to 45 minutes, but you avoid phone wait times.

What Medicare covers and what you choose during enrollment

Medicare has four parts. Part A covers hospital stays, skilled nursing care, and hospice — it is automatic and free for most people at 65. Part B covers doctor visits, outpatient care, and preventive services; you pay a monthly premium (about $175 in 2024, though this changes yearly). Part D is prescription drug coverage, offered by private insurers, and you choose a plan during enrollment. Part C (Medicare Advantage) is an alternative to Parts A and B offered by private insurers; it bundles hospital and doctor coverage into one plan.

During enrollment, you decide whether to take Part B (you can decline if you have employer coverage, but you must sign up later). You choose a Part D plan if you want prescription drug coverage — if you do not choose one, you can still sign up later but may face a penalty. If you want Part C instead of traditional Medicare, you choose that plan during enrollment.

You do not have to make all these decisions at once. Part A starts automatically. You can enroll in Part B and Part D during your initial window, or you can enroll in Part B now and Part D later (though waiting on Part D triggers the penalty). Part C has its own enrollment periods throughout the year.

Timing your enrollment to avoid delays

Start the process two months before you turn 65, not three. This gives you time to gather documents, ask questions, and handle any issues before your coverage needs to start. If you wait until the month you turn 65, you risk processing delays — Medicare can take two to four weeks to process enrollment, and you do not want to be uninsured while waiting.

If you are signing up online, you can submit your process when ready. If you are calling or visiting an office, ask when your coverage will start. Coverage typically begins on the first day of the month you turn 65 if you enroll by the 15th of the previous month. If you enroll after the 15th, coverage may start the following month.

If you are delaying enrollment because of employer coverage, sign up within one month of losing that coverage. Do not wait until month eight of your eight-month window — processing delays could push you past the important date.

Frequently Asked Questions

What if I turn 65 while still working?

You can delay Medicare if your employer plan has 20 or more employees. You do not have to sign up at 65. Once you retire or lose that coverage, you have eight months to enroll without penalty. If your employer has fewer than 20 employees, you should sign up at 65 even if you are still working.

Can I sign up for Medicare after I turn 65?

Yes, but you may face a penalty. You have three months after your 65th birthday to sign up during your initial enrollment window. After that, you can still sign up, but Part B and Part D penalties explore. The only exception is if you have may have access to employer coverage, which gives you eight months after that coverage ends.

Do I have to take Part B at 65?

You must sign up for Part B during your enrollment window if you want coverage to start at 65. If you have employer coverage, you can decline Part B and sign up later when that coverage ends. If you decline Part B without employer coverage, you pay a penalty when you eventually enroll.

What if I miss my enrollment window by a few days?

Missing the window by even one day means you are outside your initial enrollment period. You can still sign up, but penalties explore when ready. The only way to avoid the penalty is if you have may have access to employer coverage or another special circumstance. Contact Medicare at 1-800-MEDICARE to ask if your situation qualifies for a special enrollment period.

Does my spouse have to sign up at the same time?

No. Each person has their own enrollment window based on their own birthday. Your spouse signs up during the three-month window around their 65th birthday, regardless of when you signed up. If you both have employer coverage, you can both delay until that coverage ends.