How to enroll in Medicare

You enroll in Medicare by contacting Social Security, Medicare directly, or your state health insurance counselor — the route depends on whether you are already receiving Social Security benefits and when your 65th birthday falls. Most people become may be able to access at age 65, but you can enroll starting three months before that birthday and up to three months after. If you miss this window, you may face a permanent penalty on your premiums, so the timing matters.

The enrollment process itself is straightforward: you provide your name, Social Security number, date of birth, and citizenship or immigration status. You choose which parts of Medicare you want (Part A covers hospital care, Part B covers doctor visits and outpatient services), and you decide whether to add prescription drug coverage through Part D. The whole process takes 15 to 30 minutes by phone or online.

Key Takeaways

  • You can enroll in Medicare starting three months before your 65th birthday and must do so by three months after, or face a permanent increase to your premiums.
  • If you are already receiving Social Security, Medicare will contact you automatically about two months before your birthday — you do not have to do anything unless you want to change your choices.
  • You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years; Part B (medical insurance) costs a monthly premium that varies based on your income.

When your enrollment window opens and closes

Your Initial Enrollment Period is seven months long: it starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, you can enroll starting in March and must do so by September. You can enroll in any month during this window — there is no advantage to doing it early or late within the period, except that coverage starts on the first day of the month you enroll (or the first day of the following month if you enroll after the 15th).

If you do not enroll during your Initial Enrollment Period, you enter a General Enrollment Period that runs January 1 through March 31 each year. Coverage under General Enrollment does not start until July 1 of that year, so you lose months of coverage. Additionally, you will pay a permanent 10 percent increase to your Part B premium for each full year you delayed enrollment — this penalty stays with you for life.

There are exceptions: if you are still working and covered by your employer's health plan, you may be able to delay enrollment without penalty. You will need to show proof of employer coverage when you eventually enroll. Similarly, if you are a federal employee, railroad retiree, or have coverage through a spouse's plan, different rules may explore.

Three ways to enroll

Online at Medicare.gov is the fastest route if you are comfortable with a computer. Go to Medicare.gov, click "Sign up for Medicare," and create an account using your email and a password. You will answer questions about your age, citizenship, and whether you want Part A, Part B, and Part D. The system will tell you your estimated premiums before you confirm. You can complete this in one sitting and will receive a confirmation number when ready.

By phone at 1-800-MEDICARE (1-800-633-4227) works if you prefer to speak with someone or do not have internet access. The line is open 24 hours a day, seven days a week. Have your Social Security number, date of birth, and citizenship information ready. The representative will walk you through the same questions as the online form and can answer questions about costs and coverage options. The call usually takes 20 to 30 minutes.

In person at your local Social Security office is an option if you want to hand over documents or need help in your language. You can find your nearest office at ssa.gov/locator. 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 at most offices, but calling ahead can reduce wait time.

What documents and information you will need

Before you contact Medicare or Social Security, gather these items:

  • Your Social Security number
  • Your date of birth
  • Proof of U.S. citizenship or legal residency (passport, birth certificate, naturalization papers, or green card)
  • Your current mailing address
  • Information about any current health insurance (employer plan, COBRA, or private coverage)

If you are enrolling in Part D (prescription drug coverage), have a list of your current medications and the pharmacies where you fill them. This helps you choose a plan that covers your drugs at a good price. You do not need to provide this information to enroll, but having it ready makes the process smoother.

If you are claiming an exception to the late enrollment penalty (such as employer coverage), bring documentation of that coverage — usually a letter from your employer's benefits office or a copy of your insurance card.

What happens after you enroll

Once you enroll, Medicare will send you a Medicare card in the mail within two to four weeks. Your coverage starts on the first day of the month you enroll (or the first day of the following month if you enroll after the 15th). You do not have to do anything else unless you chose Part D — if you did, your prescription drug plan will send you a separate card with your plan details.

If you enrolled online or by phone, you will receive a confirmation number when ready. Write it down or save it. You can use this number to check the status of your process at Medicare.gov or by calling 1-800-MEDICARE.

If you are already receiving Social Security benefits, Medicare will contact you automatically about two months before your 65th birthday. You will receive a notice in the mail explaining your options. You can accept the default choices (Part A and Part B), make changes online at Medicare.gov, or call 1-800-MEDICARE. If you do nothing, you will be enrolled in Part A and Part B automatically.

Common mistakes to avoid

The most costly mistake is missing your enrollment important date. If you turn 65 and do not enroll within your seven-month Initial Enrollment Period, you will pay a permanent 10 percent penalty on Part B premiums for every year you were late. This penalty does not go away, even if you enroll later. The only exception is if you had employer coverage or other may have access to coverage — in that case, you have until eight months after that coverage ends to enroll without penalty.

Another common error is not choosing Part D when you first enroll. If you do not have prescription drug coverage and later decide you want it, you will pay a permanent late enrollment penalty of about 1 percent of the national average Part D premium for each month you were without coverage. This penalty also stays with you for life. If you think you might need prescription drugs in the future, enroll in Part D even if you do not take medications now.

A third mistake is not updating your information if you move, change your name, or change your citizenship status. Contact Medicare at 1-800-MEDICARE or update your information online at Medicare.gov to make sure your card and bills go to the right address.

If you are still working or have other coverage

If you are still working and your employer offers health insurance, you may not need to enroll in Part B right away. You can delay Part B without penalty as long as you are actively employed and covered by your employer's plan. However, you should still enroll in Part A at 65, since it is usually free and covers hospital care.

When you leave your job or lose employer coverage, you have eight months to enroll in Part B without penalty. Contact Medicare within that window to avoid the late enrollment penalty. Bring documentation of your employer coverage — usually a letter from your benefits office stating the dates you were covered.

If you have coverage through a spouse's employer plan, similar rules explore. You can delay your own enrollment as long as you are covered under their plan, but you must enroll within eight months of losing that coverage.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Yes. You can enroll starting three months before your 65th birthday. For example, if you turn 65 in September, you can enroll starting in June. Your coverage will start on the first day of the month you turn 65 (or the month after, depending on when you enroll).

What if I miss my enrollment important date?

You can still enroll during the General Enrollment Period (January 1 through March 31 each year), but your coverage will not start until July 1, and you will pay a permanent 10 percent increase to your Part B premium for each year you delayed. The only exception is if you had employer coverage or other may have access to insurance — then you have eight months after that coverage ends to enroll without penalty.

Do I have to enroll in Part B if I am still working?

No. If you are still working and covered by your employer's health plan, you can delay Part B without penalty. However, you should still enroll in Part A at 65, since it is usually free. When you leave your job, you have eight months to enroll in Part B without penalty.

How much does Medicare cost?

Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years. Part B costs a monthly premium that varies based on your income — in 2024 it ranges from about $174 to $560 per month for most people. Part D (prescription drug coverage) costs vary by plan, typically $5 to $100 per month. You will see your estimated costs before you confirm enrollment.

Can I change my Medicare choices after I enroll?

Yes. You have an annual window called the Annual Enrollment Period (October 15 through December 7 each year) to change your Part B, Part D, or Medicare Advantage coverage. Changes take effect January 1. You can also make changes if you have a may have access to life event, such as losing employer coverage or moving to a new state.