You must sign up for Medicare during specific windows, or you will pay a penalty for as long as you have Medicare

Medicare enrollment is not automatic. You have to sign up during one of three enrollment periods, or you will face a permanent monthly penalty added to your premium. The main enrollment window is the seven weeks before the month you turn 65. If you miss that window, you can still sign up during the General Enrollment Period (January 1 to March 31 each year), but the penalty applies. The only way to avoid the penalty is to have had other health coverage that counts as "creditable coverage" during the time you were not signed up.

The rules are different depending on whether you are signing up for Part A (hospital insurance), Part B (medical insurance), or both. Part A has no penalty if you delay — but only if you have never worked or paid Medicare taxes. Part B and Part D (prescription drug) both carry penalties that grow the longer you wait. Understanding which enrollment period applies to you now will save you money later.

Key Takeaways

  • Your Initial Enrollment Period is the seven weeks before the month you turn 65, the month you turn 65, and the three months after — a total of seven months to sign up without penalty.
  • 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 monthly penalty on Part B and a 1 percent monthly penalty on Part D for the rest of your life.
  • If you have health insurance through your job or your spouse's job, you may be able to delay Part B without penalty — but you must have written proof that your coverage counts as creditable.
  • Part A (hospital insurance) has no lifetime penalty for late sign-up if you have never worked or paid Medicare taxes, but most people do pay taxes and should sign up on time.
  • You sign up through 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 when you turn 65

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. That gives you seven months total. For example, if you turn 65 in June, your enrollment period runs from March through September. You can sign up any time during those seven months, and your coverage will begin on the first day of the month you turn 65 (or the first day of the following month, depending on when you sign up).

If you sign up in the three months before you turn 65, your Part A and Part B coverage begins the month you turn 65. If you sign up in the month you turn 65 or later, your coverage begins the month after you sign up. This timing matters if you have a gap in health insurance — signing up early keeps that gap short.

You do not have to wait until you are 65 to start the process. You can contact Medicare or visit Medicare.gov three months before your birthday to ask questions and gather the documents you will need. Social Security will send you a notice about three months before you turn 65, but do not rely on that notice alone — it is your responsibility to sign up.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your seven-month Initial Enrollment Period, you enter the General Enrollment Period. This runs January 1 through March 31 each year. You can sign up then, and your coverage will begin July 1 of that year. But you will pay a penalty.

The Part B penalty is 10 percent of the standard monthly premium for each 12-month period you were not signed up. If you were not signed up for two years, your penalty is 20 percent, and you pay it for the rest of your life. The Part D (prescription drug) penalty is 1 percent of the national average premium for each month you were not signed up. These penalties are permanent — they do not go away after a certain time.

The only exception is if you had other health insurance that counts as "creditable coverage" during the time you were not signed up. Creditable coverage means a health plan through your job, your spouse's job, TRICARE, the Veterans Health Administration, or certain other sources. You will need written proof from that plan showing the dates you were covered. If you have that proof, you can sign up during General Enrollment without penalty.

Delaying Part B if you have job-based health insurance

If you or your spouse are still working and have health insurance through that job, you may be able to delay Part B without penalty. This is called the "Special Enrollment Period for individuals with group health plan coverage." You can sign up for Part B later without the 10 percent penalty, as long as you sign up within eight months of the date your job-based coverage ends or your employment ends, whichever comes first.

To use this exception, you must have written proof that your coverage was creditable. Ask your employer's benefits office or health plan for a letter stating the dates you were covered and confirming that the plan meets Medicare's definition of creditable coverage. Keep this letter — you will need it when you sign up for Medicare, and you may need it to prove you do not owe a penalty.

Part A (hospital insurance) does not have a penalty for delay if you have job-based coverage, but Part B does. If you delay Part B, you should still sign up for Part A during your Initial Enrollment Period. Part A is free for most people, and signing up early protects you in case you need hospital care before you sign up for Part B.

Part D (prescription drug) enrollment and the late penalty

Part D has its own enrollment rules and its own penalty. You must sign up for Part D during your Initial Enrollment Period (the same seven-month window as Part A and Part B) or during the General Enrollment Period. If you do not have prescription drug coverage through another source, you should sign up during your Initial Enrollment Period.

The Part D penalty is 1 percent of the national average monthly premium for each month you were not signed up. Like the Part B penalty, this is permanent. If you go without Part D coverage for 18 months, your penalty is 18 percent of the average premium, and you pay it every month for the rest of your life.

You can avoid the Part D penalty if you have other prescription drug coverage that counts as creditable. This includes coverage through your job, your spouse's job, TRICARE, the Veterans Health Administration, or a retiree health plan. You will need written proof of this coverage. If you have creditable coverage and then lose it, you have 63 days to sign up for Part D without penalty.

How to sign up for Medicare

You can sign up through three main routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Medicare.gov has a tool that walks you through the sign-up process step by step. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage you have.

If you are already receiving Social Security benefits, you will be signed up for Part A and Part B automatically the month you turn 65. You do not have to do anything. If you are not yet receiving Social Security, you must sign up for Medicare separately — Social Security will not do it for you.

The phone line 1-800-MEDICARE is open Monday through Friday, 8 a.m. to 8 p.m. Eastern time. Representatives can answer questions about enrollment, help you sign up, and send you forms by mail. If you prefer to sign up in person, your local Social Security office can help. You can find the office nearest you on the Social Security website.

Questions to ask your doctor or Medicare before you sign up

Before you sign up, ask your current doctor whether they accept Medicare. Not all doctors do, and switching doctors can be disruptive. You can search for doctors who accept Medicare on Medicare.gov's "Care Provider Search" tool. If your doctor does not accept Medicare, ask whether they can refer you to someone in your area who does.

Ask Medicare whether you need to sign up for all parts or whether you can delay any part. This depends on your work history, your current coverage, and your health needs. If you have questions about penalties, ask Medicare directly — the rules are specific to your situation, and a representative can tell you whether you owe a penalty or whether an exception applies to you.

If you have a chronic condition and take prescription drugs, ask your pharmacist which Medicare Part D plans cover your medications. Not all plans cover all drugs, and some require you to try a cheaper drug first. Knowing this before you sign up helps you choose a plan that fits your needs.

Frequently Asked Questions

What if I turn 65 but I am still working?

You can delay Part B without penalty if you have health insurance through your job. You must sign up for Part A during your Initial Enrollment Period (it is free and protects you in case of hospitalization). When you leave your job or lose that coverage, you have eight months to sign up for Part B without penalty. Get written proof from your employer that your coverage is creditable.

Can I sign up for Medicare before I turn 65?

You can contact Medicare and start gathering documents three months before you turn 65, but you cannot officially sign up until your Initial Enrollment Period begins (three months before the month you turn 65). You can sign up online at Medicare.gov, by phone, or in person at Social Security.

What if I missed the important date by a few weeks?

If you missed your Initial Enrollment Period, you can sign up during the General Enrollment Period (January 1 to March 31 each year), but you will pay a penalty on Part B and Part D. The penalty is permanent. The only way to avoid it is to show that you had creditable coverage during the time you were not signed up.

Do I have to sign up for Part D if I do not take prescription drugs?

You do not have to sign up for Part D now, but if you do not have other prescription drug coverage and you do not sign up, you will pay a 1 percent monthly penalty when you do sign up later. This penalty is permanent. If you think you might need prescriptions in the future, signing up during your Initial Enrollment Period protects you.

What counts as creditable coverage?

Creditable coverage includes health insurance through your job, your spouse's job, TRICARE, the Veterans Health Administration, a retiree health plan, or certain other sources. You must have written proof from that plan showing the dates you were covered. A letter from your employer's benefits office or health plan is the best proof.