When and how to enroll in Medicare

You can enroll in Medicare starting three months before the month you turn 65. The enrollment window lasts seven months total — three months before, the month you turn 65, and three months after. If you miss this window, you may pay a penalty for the rest of your life, so the timing matters.

There are three ways to enroll: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online is fastest — you can complete it in about 15 minutes if you have your Social Security number and birth date ready. The phone line has wait times but staff can answer questions as you go. In-person enrollment at Social Security takes longer but works well if you need help with forms.

You do not have to wait until you turn 65 to start the process. Many people begin three months before their birthday so the coverage starts on the first day of their birth month. This is the smoothest approach because there is no gap between your current coverage and Medicare.

Key Takeaways

  • You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office, and you should start three months before you turn 65.
  • Your enrollment window is seven months long — three months before your 65th birthday, the month you turn 65, and three months after — and missing it can result in permanent penalties.
  • Medicare Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years, but Part B (doctor visits) has a monthly premium you must pay.
  • If you are still working and have health insurance through your job, you may be able to delay Part B without penalty, but you must tell Medicare about your work coverage.
  • After you enroll, your Medicare card arrives in the mail within two weeks, and your coverage begins on the first day of the month you turn 65 or the month you enroll, whichever is later.

What documents and information you need to enroll

Gather these items before you start the enrollment process: your Social Security number, your birth date, your citizenship or immigration status, and information about any current health insurance you have. If you are enrolling by phone or in person, bring a photo ID as well.

If you are still working or your spouse is still working, have your employer's health insurance information ready. Medicare needs to know whether you have coverage through a current job because it affects whether you can delay Part B without a penalty. If you are retired and have coverage from a former employer or union, bring that information too — it may affect your Part B premium.

You will also need to decide which Medicare plan you want. Part A covers hospital stays, skilled nursing, hospice, and some home health care. Part B covers doctor visits, outpatient care, and medical equipment. Most people enroll in both. Some people also choose Part D (prescription drug coverage) or a Medigap or Medicare Advantage plan at the same time, though you can add these later.

Enrolling online at Medicare.gov

Go to Medicare.gov and look for the "Sign Up" button on the homepage. You will create a login or use an existing one. The form asks for your Social Security number, birth date, and citizenship status. It takes about 10 to 15 minutes to complete.

After you submit the form, you will see a confirmation page. Write down your confirmation number or print the page. Medicare will send you a letter in the mail within two weeks with your Medicare number and the date your coverage begins. Your physical Medicare card arrives separately, usually within two weeks as well.

If you run into trouble on the website, you can call 1-800-MEDICARE and ask for help. The phone line is open Monday through Friday, 8 a.m. to 8 p.m. Eastern time, and Saturday 9 a.m. to 1 p.m. Eastern time.

Enrolling by phone or in person

Call 1-800-MEDICARE to enroll over the phone. Have your Social Security number, birth date, and current insurance information ready. The representative will walk you through the form and answer questions. The call usually takes 20 to 30 minutes. You will receive a confirmation number at the end.

To enroll in person, visit your local Social Security office. You can find the nearest one at ssa.gov or by calling 1-800-772-1213. Bring your photo ID, Social Security card (or a document showing your number), birth certificate, proof of citizenship or immigration status, and information about any current health insurance. Staff will help you fill out the form and answer questions. Bring a list of any questions you have, because in-person appointments can move quickly.

Whether you enroll by phone or in person, you will receive a confirmation number before you leave. Ask the representative to mail you a written confirmation as well, so you have a record.

What happens after you enroll

Once you submit your enrollment, Medicare processes it within two weeks. You will receive a letter with your Medicare number and the date your coverage begins. Your physical Medicare card arrives separately, usually within two weeks. Do not wait for the card to start using your benefits — your coverage is active on the date listed in the letter, even if the card has not arrived yet.

If you need to see a doctor before your card arrives, give them your Medicare number from the letter. They can look up your coverage in their system. Keep the letter in a safe place until the card arrives.

You will also receive a document called "Your Medicare Coverage" that explains what Part A and Part B cover, what you pay, and how to find doctors and hospitals in the Medicare network. Read this carefully, because it tells you what to expect when you use your benefits.

If you are still working or have employer coverage

If you or your spouse are still working and have health insurance through your job, you may be able to delay enrolling in Part B without paying a penalty. This is called having creditable coverage. Your employer's insurance must cover at least as much as Medicare Part B does.

To delay Part B, you must tell Medicare that you have work coverage when you enroll in Part A. You do this by checking a box on the enrollment form that says you have current employer coverage. Keep proof of this coverage — your insurance card, a letter from your employer, or a benefits document — because you will need it later when you do enroll in Part B.

When you or your spouse stops working, you have eight months to enroll in Part B without penalty. This period is called your Special Enrollment Period. If you miss this window, you will pay a penalty of 10% for each year you delayed, and the penalty is permanent. Contact Medicare as soon as your work coverage ends to enroll in Part B.

Late enrollment penalties and how to avoid them

If you miss your initial enrollment window and do not have a reason Medicare accepts, you will pay a penalty for Part B. The penalty is 10% of the standard Part B premium for each full year you delayed. If the standard premium is $165 per month and you delayed for two years, your penalty would be 20% — an extra $33 per month for life.

Medicare accepts certain reasons for late enrollment without penalty. These include having creditable coverage through an employer or union, being a federal employee with federal health insurance, or being a veteran with VA coverage. If any of these explore to you, tell Medicare when you enroll and provide proof.

If you missed your window and do not have an accepted reason, you can still enroll during the General Enrollment Period, which runs January 1 through March 31 each year. Your coverage would begin July 1. You would pay the penalty, but at least your coverage would start. Contact Medicare to discuss your situation — sometimes they can review whether you have a valid reason for the delay.

Frequently Asked Questions

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

No, if you have health insurance through your current job, you can delay Part B. But you must tell Medicare you have work coverage when you enroll in Part A. When you stop working, you have eight months to enroll in Part B without penalty. If you miss that window, you pay a permanent penalty.

What if I turn 65 but am not a U.S. citizen?

You can enroll in Medicare if you are a lawful permanent resident (green card holder) and have lived in the United States for at least five years. You will need to show proof of your immigration status when you enroll. Contact Medicare at 1-800-MEDICARE to discuss your specific situation.

Can I change my mind after I enroll?

Yes. You have until the end of the calendar year to make changes to your Part B, Part D, or Medigap coverage. Changes take effect January 1. If you enrolled in a Medicare Advantage plan, you have until December 7 to switch to Original Medicare or a different plan.

What if I miss the enrollment important date?

You can still enroll during the General Enrollment Period from January 1 through March 31, and coverage begins July 1. However, you will likely pay a permanent penalty on your Part B premium. Contact Medicare to see if you have a valid reason for the delay that would waive the penalty.

When does my Medicare coverage actually start?

Coverage begins on the first day of the month you turn 65, or the first day of the month after you enroll, whichever is later. If you enroll three months before your birthday, coverage starts the first day of your birth month. If you enroll after you turn 65, coverage starts the first day of the following month.