You can sign up for Medicare starting at age 65, but the exact timing matters for your costs

Medicare may be able to access begins the month you turn 65, regardless of whether you are still working. You do not have to wait until you retire. However, the month you sign up determines your premiums for life — sign up late and you pay a permanent penalty on top of your monthly bill. The window to sign up without penalty is your Initial Enrollment Period, which runs for seven months: three months before the month you turn 65, the month itself, and three months after.

If you miss that window, you can still sign up later, but you will owe a late enrollment penalty unless you had health coverage through an employer with 20 or more employees. That penalty stays on your bill permanently, even if you switch plans later. The penalty amount depends on how many months you delayed and which part of Medicare you are signing up for.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after — sign up during this window to avoid permanent penalties.
  • If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty, but you must sign up for Part A when you turn 65.
  • Late enrollment penalties are permanent and explore every month you have Medicare, so delaying costs money for the rest of your life.
  • You can sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Special enrollment periods exist if you lose employer coverage or move to a new state, giving you a second chance to sign up without penalty.

What happens if you sign up on time versus late

Signing up during your seven-month Initial Enrollment Period means your coverage starts the month you turn 65 (or the month after, depending on when in the month you sign up). Your premiums are the standard rate with no penalty added. This is the least expensive path.

If you sign up after your Initial Enrollment Period ends, your coverage does not start when ready — there is usually a delay of one to three months. More importantly, you owe a late enrollment penalty. For Part B, the penalty is 10 percent of the standard monthly premium for each full year you delayed. If you delayed for three years, you pay 30 percent extra every month for life. For Part D (prescription drug coverage), the penalty is 1 percent of the national average premium per month of delay, also permanent.

The only exception is if you had health insurance through an employer with 20 or more employees during the time you delayed. If that applies to you, you have eight months after that coverage ends to sign up for Part B without penalty. You still must sign up for Part A at 65.

Signing up while you are still working

If you are still employed and your employer offers health coverage, you have options. You must sign up for Part A (hospital insurance) when you turn 65, even if you stay on your employer plan. Part A has no monthly premium if you or your spouse paid Medicare taxes for at least 10 years, so there is no cost to signing up.

You may be able to delay Part B (medical insurance) without penalty if your employer has 20 or more employees and you are actively working. This is called the employer coverage exception. You do not sign up for Part B while you are covered by the employer plan. When you leave that job or lose the coverage, you have eight months to sign up for Part B without penalty. If you miss that window, the late enrollment penalty applies.

Part D (prescription drug coverage) works differently. If your employer plan covers drugs, you should check whether it is considered creditable coverage — meaning it covers drugs at least as well as Medicare Part D. If it is, you can delay Part D without penalty. If it is not, you should sign up for Part D during your Initial Enrollment Period to avoid the permanent penalty.

How to sign up and what you need

You can sign up for Medicare in three ways: 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 usually fastest if you have a Social Security account set up.

You will need your Social Security number, proof of citizenship or legal residency (such as a birth certificate, passport, or naturalization papers), and proof of age. If you are signing up by phone or in person, bring these documents with you. If you are signing up online, you can upload images of them or have them mailed in later.

If you are still working and using the employer coverage exception for Part B, tell Medicare that when you sign up. You will sign up for Part A only, and Part B will be added later when you provide proof that your employer coverage ended.

Special enrollment periods: a second chance if you miss the important date

If you missed your Initial Enrollment Period, you may still have a way to sign up without penalty through a Special Enrollment Period. These are triggered by specific life events, and the rules are strict.

The most common Special Enrollment Period is triggered by losing employer health coverage. If your employer coverage ends, you have eight months from the date it ends to sign up for Part B without penalty. You must provide proof that the coverage ended — usually a letter from your employer or insurance company stating the end date.

Other Special Enrollment Periods exist if you move out of your plan's service area, if you are a U.S. citizen living abroad and return to the United States, or if you are a Native American or Alaska Native. Each has different rules and time windows. Call 1-800-MEDICARE to find out whether a Special Enrollment Period applies to your situation.

Penalties and how they are calculated

Late enrollment penalties are permanent and compound over time. For Part B, the penalty is 10 percent of the standard monthly premium ($164.90 in 2024, though this changes yearly) for each full year you delayed. If you delayed for one year, you pay an extra $16.49 per month for life. If you delayed for five years, you pay an extra $82.45 per month for life.

For Part D, the penalty is 1 percent of the national average premium per month of delay. In 2024, the national average is roughly $34, so one year of delay costs about $4.08 extra per month for life. These amounts change yearly, but the penalty structure stays the same.

The penalty does not go away if you switch plans, move to a different state, or change your coverage type. It follows you as long as you have Medicare. The only way to avoid it is to sign up during your Initial Enrollment Period or a Special Enrollment Period.

What to do if you already missed the important date

If you are past your Initial Enrollment Period and do not may have access to for a Special Enrollment Period, you can still sign up, but the late enrollment penalty will explore. Call 1-800-MEDICARE to discuss your situation. A representative can tell you exactly what your penalty will be and help you understand your options.

Some people choose to wait and sign up during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage would start July 1 if you sign up during this window. However, you will still owe the late enrollment penalty, and the delay means you go longer without coverage. There is no advantage to waiting unless you are gathering documents or need time to decide between plans.

If you believe you have a valid reason for missing the important date — such as a language barrier, a serious illness, or a clerical error by Social Security — you can request a waiver of the late enrollment penalty. This is rare and requires documentation, but it is worth asking about if your situation was genuinely beyond your control.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

Your Initial Enrollment Period starts three months before the month you turn 65, so yes, you can sign up early. Signing up at 64 and a half is common and avoids the rush. Your coverage will not start until the month you turn 65, but you will be registered and ready.

What if I am still working and do not want Medicare yet?

You must sign up for Part A at 65 even if you are still working, because it has no premium. You can delay Part B if your employer has 20 or more employees and you are actively working. When you leave that job, you have eight months to sign up for Part B without penalty. If you miss that window, the permanent penalty applies.

Do I have to sign up for all parts of Medicare at the same time?

No. You must sign up for Part A at 65. You can delay Part B if you have employer coverage. You can delay Part D if your employer plan covers drugs as well as Medicare would. Each part has its own enrollment period and its own late penalty, so you can stagger them if your situation allows.

What happens to my employer health insurance when I turn 65?

Your employer coverage does not automatically end when you turn 65. You keep it as long as you are employed and the employer offers it. However, Medicare becomes your primary payer once you are enrolled, and your employer plan becomes secondary. You should tell your employer's benefits office that you have enrolled in Medicare so they can coordinate coverage correctly.

Can I change my mind after I sign up?

Yes, during your Initial Enrollment Period you can change your choices. After that period ends, you can make changes only during the Annual Enrollment Period (October 15 to December 7 each year) or if you may have access to for a Special Enrollment Period. Changes made during Annual Enrollment take effect January 1.