When to Sign Up for Medicare: Ages and Deadlines That Matter

You can sign up for Medicare starting at age 65, but the exact timing depends on whether you are still working and whether you have health coverage through your job

Most people become may be able to access for Medicare on the first day of the month they turn 65. You do not have to wait until your birthday itself — the month matters. If you turn 65 on any day in March, you can sign up starting March 1. The window to sign up without a penalty is normally three months before the month you turn 65, the month itself, and three months after — a seven-month span called your Initial Enrollment Period.

If you are still working and covered by your employer's health plan, you may be able to delay signing up without facing a penalty, but only if your employer has 20 or more employees. The rules are different if you are self-employed or work for a smaller company. Signing up late — after your Initial Enrollment Period ends — can cost you more in premiums for the rest of your life, so the timing matters even if you think you do not need Medicare yet.

Key Takeaways

Your Initial Enrollment Period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
If you are covered by an employer health plan with 20 or more employees, you can delay Medicare without penalty, but you must sign up within eight months of leaving that job or losing that coverage.
Signing up late triggers a permanent penalty on your Part B and Part D premiums unless you have proof of continuous coverage through an employer or spouse's employer.
You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
If you are already receiving Social Security before 65, Medicare will be mailed to you automatically three months before you turn 65.

What happens if you sign up during your Initial Enrollment Period

Signing up during your seven-month Initial Enrollment Period means your coverage can start as early as the first day of the month you turn 65, with no waiting period and no penalty. Most people sign up for Part A (hospital insurance) and Part B (medical insurance) at the same time. Part A is usually free if you or your spouse paid Medicare taxes while working. Part B has a monthly premium that changes each year.

If you sign up in the month you turn 65 or in the three months after, your coverage will start on the first day of the month after you sign up. For example, if you turn 65 on March 15 and sign up on April 10, your coverage begins May 1. This delay is why signing up early — in the three months before you turn 65 — is often the safest choice: it guarantees coverage starts the month you turn 65.

Delaying Medicare if you are still working

If you are covered by a health plan through your current job, you may not need Medicare right away. You can delay Part B without penalty if your employer has 20 or more employees and you are actively working. This rule applies whether the coverage is through your own job or your spouse's job. Part A (hospital insurance) does not have the same delay option — you can sign up for Part A without signing up for Part B, and Part A will not trigger a penalty even if you delay.

The catch is timing: once you leave your job or lose your employer coverage, you have eight months to sign up for Part B. If you wait longer than eight months, you will pay a permanent 10 percent increase in your Part B premium for each year you were late. This penalty stays with you for life, even if you switch plans later. If your employer has fewer than 20 employees, you must sign up for Medicare when you turn 65, even if you are still working.

To avoid a penalty, you need to prove you had employer coverage. Keep your health plan documents, pay stubs, or a letter from your employer stating the coverage dates and number of employees. You will need this proof when you sign up.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your seven-month Initial Enrollment Period and you do not have a valid reason to delay (such as employer coverage), you enter a General Enrollment Period each year from January 1 to March 31. You can sign up during this window, but your coverage will not start until July 1 of that year. You will also pay a permanent penalty on your Part B premium: 10 percent more for each full year you were may be able to access but did not sign up.

The penalty applies to Part D (prescription drug coverage) as well. If you did not sign up for Part D when you turned 65 and you go without drug coverage for 63 days or more, you will pay a permanent penalty on your Part D premium when you finally sign up. This penalty also lasts for life. The only way to avoid these penalties is to have proof of continuous coverage through an employer, a spouse's employer, or a retiree health plan.

Special situations: when you can sign up outside the normal windows

If you experience a major life event — such as losing employer coverage, moving to a new state, or losing Medicaid — you may may have access to for a Special Enrollment Period that gives you extra time to sign up without penalty. You typically have two months from the date of the event to sign up. Losing employer coverage is the most common reason for a Special Enrollment Period.

If you are receiving Social Security retirement benefits before you turn 65, Medicare will be mailed to you automatically about three months before your 65th birthday. You do not need to do anything — your coverage will start automatically on the first day of the month you turn 65. If you are not receiving Social Security, you must sign up yourself.

If you are still working past 65 and your employer has 20 or more employees, you can request a Special Enrollment Period when you leave your job. This gives you eight months to sign up for Part B without penalty, even if you miss your Initial Enrollment Period.

How to sign up and what you will 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 the fastest. 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 delaying Part B because of employer coverage, tell Medicare when you sign up. You will need to provide the name of your employer, the number of employees, and the dates you were covered. If you are signing up based on a spouse's employer coverage, you will need your spouse's name and Social Security number as well.

After you sign up, Medicare will mail you a Medicare card within two to four weeks. Your coverage will start on the date Medicare specifies in your confirmation. Keep your confirmation letter — you will need it to prove your enrollment date if you ever need to dispute a penalty.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before the month you turn 65. If you turn 65 in June, you can sign up starting March 1. Signing up early is a good idea because it guarantees your coverage starts the month you turn 65, with no gap.

What if I am still working at 65 and do not want Medicare?

If your employer has 20 or more employees and you are actively working, you can delay Part B without penalty. You must sign up within eight months of leaving your job or losing coverage. Part A does not have the same delay option, but you can sign up for Part A alone if you want to wait on Part B.

How much does it cost to sign up for Medicare?

There is no cost to sign up. Part A is usually free if you or your spouse paid Medicare taxes while working. Part B has a monthly premium that varies by income and changes each year. In 2024, the standard Part B premium is $164.90 per month, but yours may be higher or lower depending on your income.

What happens if I sign up late?

If you sign up after your Initial Enrollment Period ends and you do not have proof of employer coverage, you will pay a permanent penalty on your Part B and Part D premiums. The penalty is 10 percent per year you were late. You can only sign up during the General Enrollment Period (January 1 to March 31), and your coverage will not start until July 1.

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

No. You can sign up for Part A alone and delay Part B if you are covered by an employer plan with 20 or more employees. However, if you delay Part B past your Initial Enrollment Period without employer coverage, you will pay a permanent penalty when you finally sign up.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.