When to Sign Up for Medicare: Deadlines and Penalties You Should Know

You must enroll in Medicare during specific windows, or you will pay a permanent penalty on your premiums

Medicare enrollment is not automatic. You have to sign up during your Initial Enrollment Period (IEP), which runs for seven months centered on your 65th birthday — three months before, the month you turn 65, and three months after. If you miss this window and do not have coverage from an employer or union, you will pay a 10% surcharge on Part B premiums for as long as you have Medicare. For Part D (prescription drug coverage), the penalty is 1% per month you go without it.

The exact timing matters because penalties are permanent, not temporary. A person who enrolls at 67 instead of 65 will pay the extra 10% for the rest of their life, even if they switch plans later. The same applies to Part D: waiting costs you money every single month you are enrolled.

There are narrow exceptions. If you have health insurance through your job or your spouse's job, you can delay enrollment without penalty — but only if that coverage is considered creditable, meaning it is at least as good as Medicare. Once that coverage ends, you have a special eight-month window to enroll without penalty. If you miss that window too, the penalties explore.

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 your IEP and do not have employer coverage, you pay a 10% permanent surcharge on Part B premiums and 1% per month on Part D premiums.
If you have health insurance through work, you can delay Medicare without penalty, but you must enroll within eight months of losing that coverage.
You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

What counts as employer coverage that lets you delay

You can delay Medicare without penalty only if your employer or your spouse's employer offers health insurance that is considered creditable. This means the coverage must be at least as comprehensive as Medicare Part A and Part B combined. Most employer plans meet this standard, but some do not — particularly retiree plans with very high deductibles or limited coverage.

Before you turn 65, ask your employer's benefits office or your health plan directly: "Is this plan considered creditable coverage for Medicare purposes?" Get the answer in writing. You will need this documentation later to prove you had a valid reason to delay. If your employer cannot or will not confirm, assume the coverage is not creditable and enroll in Medicare on time.

The eight-month window to enroll without penalty starts the month your employer coverage ends — not the month you retire, but the month the actual insurance stops. If you retire in June but your coverage continues through August, your eight-month window opens in September. Mark that date clearly, because missing it costs you permanently.

When to enroll if you are still working

If you are still working at 65 and your employer offers health insurance, you do not have to enroll in Medicare Part A or Part B right away. However, you should still enroll in Part D (prescription drug coverage) during your Initial Enrollment Period unless your employer plan includes drug coverage that is creditable. Skipping Part D enrollment costs you 1% per month in penalties, and those penalties never go away.

When you do leave your job, enroll in Medicare within eight months. Your employer should send you a notice explaining your coverage end date — keep this document. You will need it to show Medicare that you had a valid reason to delay. If you do not receive a notice, contact your benefits office and ask for written confirmation of your coverage dates.

Part A (hospital insurance) is different from Part B. Many people can enroll in Part A without penalty even after 65, because Part A does not have a monthly premium if you or your spouse paid Medicare taxes for at least 10 years. However, Part B and Part D penalties are permanent, so do not delay those.

Special enrollment periods for life changes

If you experience certain life events — losing employer coverage, moving out of your plan's service area, getting married, or losing Medicaid — you may have a special enrollment period outside your Initial Enrollment Period. These windows are usually 60 days long and do not require you to wait for the standard open enrollment season.

The most common special enrollment period is the one that opens when your employer coverage ends. You have eight months from the month coverage stops to enroll in Medicare without penalty. Other may have access to events include losing Medicaid, moving to a different state, or having your current Medicare plan leave your area. Each event has its own rules and timeline.

To use a special enrollment period, you must contact Medicare and provide proof of the may have access to event. This might be a letter from your employer, a Medicaid termination notice, or a plan cancellation letter. Do not assume you may have access to — call 1-800-MEDICARE and ask whether your situation opens a special window.

How to enroll during your Initial Enrollment Period

You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. Online enrollment is usually the fastest — you can complete it in 15 to 20 minutes if you have your Social Security number and basic health information ready.

When you enroll, you will choose between Original Medicare (Part A and Part B) or a Medicare Advantage plan (Part C). You will also choose a Part D plan if you want prescription drug coverage. These are separate decisions: you can pick Original Medicare with a standalone Part D plan, or you can pick a Medicare Advantage plan that includes drug coverage. Compare the plans available in your area before you enroll, because your choices change each year.

Coverage typically starts the first day of the month you turn 65, even if you enroll before that date. If you enroll after your birthday, coverage starts the first day of the following month. Keep your enrollment confirmation — you will need it to prove you are covered when you see a doctor.

What happens if you miss your Initial Enrollment Period

If you miss your seven-month Initial Enrollment Period and do not have employer coverage, you can still enroll, but you will face permanent penalties. Part B premiums increase by 10% for each full 12-month period you were not enrolled. Part D premiums increase by 1% for each month you were not enrolled. These penalties stay with you for life.

You can enroll during the General Enrollment Period, which runs January 1 through March 31 each year. Coverage starts July 1 of that year. This is a long wait if you miss your IEP in, say, September — you would not have coverage until the following July. During those months without coverage, you are responsible for all medical costs.

The only way to avoid these penalties is to prove you had creditable coverage or a may have access to life event. If you believe you have a valid reason to delay, contact Medicare and ask about a special enrollment period. Bring documentation: an employer letter, a Medicaid notice, or proof of loss of coverage.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before your 65th birthday, so you can enroll as early as three months before. Most people enroll during this early window to may support coverage starts on time. You cannot enroll more than three months early.

What if I am still working and my employer says I do not need Medicare?

Your employer cannot prevent you from enrolling in Medicare. However, if your employer offers creditable coverage, you can delay Part A and Part B without penalty. You should still enroll in Part D during your Initial Enrollment Period unless your employer plan covers prescriptions. Get written confirmation from your employer that your coverage is creditable.

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

No. Part A and Part B are separate. You can enroll in Part A without Part B if you have employer coverage. However, if you delay Part B and later lose your employer coverage, you have only eight months to enroll in Part B without penalty. After that, the 10% surcharge applies permanently.

What if I turned 65 more than three months ago and did not enroll?

You missed your Initial Enrollment Period. You can still enroll during the General Enrollment Period (January 1 through March 31), but coverage will not start until July 1, and you will pay permanent penalties on Part B and Part D. Contact Medicare at 1-800-MEDICARE to ask whether you have a special enrollment period due to a may have access to event.

Can I change my Medicare plan after I enroll?

Yes, but only during specific windows. You can switch plans during the Annual Enrollment Period (October 15 through December 7 each year), and changes take effect January 1. If you have a may have access to life event, you may have a special enrollment period. Outside these windows, you are locked into your current plan until the next Annual Enrollment Period.

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.