You must sign up for Medicare during specific windows, or you may face higher costs for the rest of your life

Medicare enrollment is not automatic. You have to take action during one of three enrollment periods, or you risk paying a permanent penalty on your premiums. The main window is your Initial Enrollment Period, 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, you can still sign up during the General Enrollment Period (January 1 to March 31 each year), but you will pay a 10 percent penalty for each year you delayed, and that penalty stays on your Part B and Part D premiums forever.

There are exceptions. If you have health insurance through your job or your spouse's job when you turn 65, you may not have to sign up right away — but you must understand your specific situation, because the rules differ depending on the size of your employer and the type of coverage you have. Waiting without a valid reason is the most common and most expensive mistake people make with Medicare timing.

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 Initial Enrollment Period, you can sign up during General Enrollment (January 1 to March 31), but you will pay a 10 percent penalty on Part B and Part D premiums for each year you delayed, and this penalty is permanent.
  • If you have health insurance through an employer with 20 or more employees, you may be able to delay Medicare without penalty, but you must notify Social Security within eight months of losing that coverage.
  • Special Enrollment Periods exist for people who lose employer coverage, move to a new state, or experience other may have access to life events, and these periods have their own important date.
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Your Initial Enrollment Period: The seven-month window around your 65th birthday

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 enrollment period runs from March through September. During these seven months, you can sign up for Medicare Part A (hospital insurance) and Part B (medical insurance) without any penalty, and you can also choose a prescription drug plan (Part D) or a Medicare Advantage plan.

The exact date you sign up within this window matters for when your coverage starts. If you sign up during the three months before your birthday month, your coverage begins on the first day of the month you turn 65. If you sign up in the month you turn 65, coverage starts the first day of the following month. If you sign up in the three months after, coverage starts the first day of the month after you sign up. This timing affects when you stop paying premiums to your current insurance and when Medicare begins paying its share of your medical bills.

Most people are automatically enrolled in Part A at 65 if they have been receiving Social Security benefits. You can check your status by logging into your Social Security account online or by calling Social Security at 1-800-772-1213. However, you are not automatically enrolled in Part B, so you must take that step yourself during your Initial Enrollment Period, even if Part A is already in place.

General Enrollment Period: The backup window from January to March

If you miss your Initial Enrollment Period, you can sign up during the General Enrollment Period, which runs January 1 to March 31 every year. Coverage begins July 1 of that year. However, signing up during General Enrollment triggers a permanent penalty on your Part B premium of 10 percent for each full year you delayed past your Initial Enrollment Period. If you were supposed to sign up at 65 and did not sign up until age 68, you owe a 30 percent penalty on Part B for the rest of your life.

The same 10 percent annual penalty applies to Part D (prescription drug coverage). If you go without Part D coverage and then sign up later, you pay the penalty even if you never fill a prescription. The penalty is calculated based on the national average premium at the time you sign up, so it changes each year, but once it is added to your premium, it does not go away.

General Enrollment is a safety net, not a preferred route. It exists for people who genuinely did not know they needed to sign up or who faced circumstances that prevented them from enrolling on time. If you are approaching or past 65 and have not yet signed up, contact Medicare or Social Security when ready to understand whether you may have access to for a Special Enrollment Period (which has no penalty) or whether General Enrollment is your only option.

Special Enrollment Periods: Exceptions when you can sign up without penalty

You may may have access to for a Special Enrollment Period if you have a may have access to life event or circumstance. These periods allow you to sign up outside the normal windows without paying the permanent penalty. The most common may have access to events are losing employer health insurance, moving to a new state, or experiencing a change in your family status.

If you have health insurance through your job or your spouse's job when you turn 65, you may not have to sign up for Medicare right away. If your employer has 20 or more employees, you can usually delay Part B without penalty. However, you must sign up for Part A at 65 (unless you are still working and have family coverage through your employer). When you leave that job or lose the coverage, you have eight months to sign up for Part B without penalty. If you wait longer than eight months, the permanent 10 percent penalty applies.

Other may have access to events include moving to a different state, losing Medicaid coverage, or having a change in your Medicare Advantage or Part D plan that affects your coverage. Each event has its own enrollment window, usually 60 days. You will need to provide proof of the may have access to event — such as a letter from your employer confirming the end of coverage or a notice from your state Medicaid program. Contact Medicare at 1-800-MEDICARE to report your event and learn the exact important date for your situation.

How to sign up: Online, by phone, or in person

You can sign up for Medicare through three main channels. The easiest and fastest is online at Medicare.gov. You will need to create an account or log in with your existing Social Security or Medicare account. The website walks you through choosing your coverage options and shows you plans available in your area with their costs and coverage details.

If you prefer to speak with someone, call 1-800-MEDICARE (1-800-633-4227). Representatives are available seven days a week, and they can answer questions about your specific situation, help you compare plans, and process your enrollment over the phone. The call is free, and you do not need to schedule an appointment.

You can also sign up in person at your local Social Security office. Find the nearest office at ssa.gov or by calling Social Security at 1-800-772-1213. Signing up in person takes longer than online or phone, but some people prefer it if they have complex questions or need help understanding their options.

What happens if you miss all important date

If you miss your Initial Enrollment Period and do not sign up during a General Enrollment Period or Special Enrollment Period, you cannot get Medicare coverage until the next General Enrollment Period begins on January 1. Your coverage will not start until July 1 of that year. During the months you are not covered, you are responsible for all medical costs.

More importantly, you will owe the permanent 10 percent penalty on Part B and Part D premiums for every year you delayed. This penalty is calculated from the month your Initial Enrollment Period ended. If you turn 65 in June 2024 and do not sign up until January 2027, you owe a penalty for nearly three years — roughly 30 percent added to your Part B and Part D premiums for life. The penalty is not a one-time fee; it is a percentage increase that applies to every premium payment you make.

The only way to avoid this penalty after missing your Initial Enrollment Period is to may have access to for a Special Enrollment Period. If you believe you have a may have access to event, report it to Medicare as soon as possible. Waiting makes it harder to prove the event occurred and may cost you the chance to enroll without penalty.

State-specific rules and employer coverage details

A few states have their own Medicaid programs that interact with Medicare enrollment. If you receive Medicaid in your state, contact your state Medicaid office to understand how signing up for Medicare affects your coverage. Some states will automatically enroll you in Medicare when you turn 65 if you are on Medicaid; others require you to take action yourself.

Employer coverage rules also vary by situation. If you work for the federal government, your employer coverage rules differ from private employers. If you are covered under your spouse's employer plan, the rules depend on whether your spouse is still working or retired. If you are covered under COBRA (continuation coverage after leaving a job), you can delay Medicare, but you must sign up within eight months of COBRA ending. Call 1-800-MEDICARE with details about your employer coverage to confirm your specific important date.

Frequently Asked Questions

What if I turn 65 but I am still working and have health insurance through my job?

If your employer has 20 or more employees, you can delay Part B without penalty. You must still sign up for Part A at 65 unless you are covered under family health insurance through your current employer. When you leave the job or lose the coverage, you have eight months to sign up for Part B without penalty. After eight months, the permanent 10 percent penalty applies for each year you delayed.

Can I sign up for Medicare before I turn 65?

Yes. Your Initial Enrollment Period begins three months before the month you turn 65. You can sign up as early as three months before your birthday. If you sign up during those three months, your coverage begins on the first day of the month you turn 65. Signing up early ensures you do not miss the important date and that your coverage starts on time.

What if I did not know I had to sign up and I missed the important date?

Contact Medicare at 1-800-MEDICARE right away. Explain your situation. You may may have access to for a Special Enrollment Period if you did not receive notice or if you had a may have access to life event. If you do not may have access to for a Special Enrollment Period, you can sign up during the next General Enrollment Period (January 1 to March 31), but you will owe the permanent penalty for the years you delayed.

Do I have to sign up for Part D at the same time as Part A and Part B?

No. You can sign up for Part D during your Initial Enrollment Period, but you do not have to. However, if you delay Part D and do not have other creditable prescription drug coverage, you will owe a permanent 1 percent penalty for each month you delayed when you finally sign up. If you do not take prescription drugs, you can skip Part D, but if you think you might need it later, signing up during your Initial Enrollment Period avoids the penalty.

What if I move to a different state after I turn 65?

Moving to a new state is a may have access to event for a Special Enrollment Period. You have 60 days from the date you move to sign up for a new Medicare Advantage or Part D plan in your new state. Contact Medicare to report your move and learn which plans are available where you now live. Your existing coverage continues until your new plan begins, so you will not have a gap in coverage.