Medicare has three main enrollment periods when you can sign up

You can enroll in Medicare during Initial Enrollment Period, which starts three months before the month you turn 65 and lasts for seven months total. You can also sign up during General Enrollment Period, which runs January 1 through March 31 each year, though you may pay a penalty if you wait. If you have coverage through an employer or union, you may have a different window called Special Enrollment Period that lets you sign up without penalty even after your Initial Enrollment Period ends.

The enrollment period you use matters because missing your window can mean paying higher premiums for the rest of your life. Medicare Part B (doctor visits) and Part D (prescription drugs) both charge a penalty of about 10 percent per year for every 12 months you delay — and that penalty stays with you permanently, even if you sign up later.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: it starts three months before you turn 65 and ends three months after.
  • If you miss your Initial Enrollment Period, you can sign up during General Enrollment (January 1 through March 31) but you will pay a permanent penalty on Part B and Part D.
  • If you are still working and covered by your employer's health plan, you may have a Special Enrollment Period that protects you from penalties even after age 65.
  • You must contact Social Security, Medicare, or your employer to find out which enrollment period applies to you — the dates are different for everyone based on your birthday.

Initial Enrollment Period: the seven-month window around your 65th birthday

Your Initial Enrollment Period begins on the first day of the third month before you turn 65. If you turn 65 in June, your period starts in March. It ends on the last day of the third month after your birthday — so if you turn 65 in June, it ends in September. That gives you seven months total to sign up for Medicare Part A (hospital insurance) and Part B (medical insurance).

You do not have to wait until the month you turn 65 to enroll. You can sign up as early as three months before. Many people sign up during the first month of their Initial Enrollment Period because it gives them time to receive their Medicare card and coverage to start on the first day of their birthday month.

If you sign up during your Initial Enrollment Period, you will not pay a late penalty on Part B. Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes while working, so there is no penalty to avoid there. But if you do not sign up for Part B during this window and you do not have a may have access to reason to delay, you will pay a penalty for as long as you have Medicare.

General Enrollment Period: January through March, with a penalty

If you miss your Initial Enrollment Period, you can sign up during General Enrollment Period, which runs January 1 through March 31 every year. Coverage starts July 1 of that year. You can use General Enrollment as many times as you need — there is no limit on how many years you can sign up this way.

The catch is that you will pay a penalty on Part B and Part D for every 12 months you delayed past your Initial Enrollment Period. If you were supposed to sign up at 65 but did not enroll until age 67, you owe a penalty for two years. That penalty is roughly 10 percent of the Part B premium per year of delay, and it is permanent — you will pay it for the rest of your life, even after you turn 80 or 90.

The penalty amount changes each year because the Part B premium changes. In 2024, the standard Part B premium was $164.90 per month, so a one-year penalty was about $16.49 per month added to your bill. If you delayed two years, you would pay about $32.98 extra per month forever. Your actual penalty depends on the year you were supposed to enroll and the year you actually enroll.

Special Enrollment Period: if you have employer coverage or union health insurance

If you are still working at 65 or older and your employer or union provides health insurance, you may have a Special Enrollment Period that lets you sign up for Medicare without paying a penalty, even after your Initial Enrollment Period ends. This is called creditable coverage — it means your employer plan is at least as good as Medicare, so the government does not penalize you for staying on it instead.

Your Special Enrollment Period usually lasts for eight months after your employment ends or your employer coverage stops, whichever comes first. If you are covered under your spouse's employer plan, the eight-month window starts when your spouse stops working or when the coverage ends. You must sign up during this eight-month window to avoid a penalty.

You need to tell Medicare that you had creditable coverage. When you sign up, you will need to provide the name of your employer or union and the dates you were covered. If you do not report it, Medicare may assume you delayed on purpose and charge you a penalty anyway. You can report it when you enroll or contact Social Security to update your record.

What happens if you miss all three enrollment periods

If you do not sign up during your Initial Enrollment Period and you do not have a Special Enrollment Period, you can still enroll during the next General Enrollment Period (January 1 through March 31). Your coverage will start July 1. But you will owe a penalty on Part B and Part D for every year you delayed.

There is no important date after which you can never sign up for Medicare. You can enroll at any age, even at 75 or 85. But the longer you wait, the higher your permanent penalty becomes. If you delayed from age 65 to age 72, you would owe a seven-year penalty on Part B and Part D.

The only way to avoid a penalty after missing your Initial Enrollment Period is to prove you had a may have access to reason to delay — usually creditable coverage through an employer or union. If you did not have that coverage, you cannot get the penalty waived.

How to find your specific enrollment dates

Your Initial Enrollment Period dates depend on your birthday, so you need to know your own dates. Social Security will send you a notice about Medicare three months before you turn 65. That notice will tell you when your Initial Enrollment Period starts and ends. You can also call Social Security at 1-800-772-1213 to ask when your enrollment period is.

If you are still working and covered by an employer plan, contact your employer's benefits office or human resources department. They can tell you whether your coverage counts as creditable coverage and what your Special Enrollment Period dates are. Bring your health plan documents or your insurance card — the benefits office will need to see them to confirm.

You can also visit Medicare.gov and use the "may be able to access and Enrollment" tool, or call Medicare directly at 1-800-MEDICARE (1-800-633-4227). Both can tell you your enrollment dates and help you understand which period applies to you.

What to do before your enrollment period starts

Start gathering information two to three months before your Initial Enrollment Period begins. 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 still working, get the name and dates of your employer coverage.

Review the Medicare plans available in your area. Part A and Part B are Original Medicare, run by the federal government. Part C (Medicare Advantage) and Part D (prescription drug coverage) are sold by private insurance companies, and the plans available to you depend on where you live. You can compare plans on Medicare.gov starting in October each year, even if your enrollment period is not until later.

If you have questions about whether you need to sign up right away or whether you can delay, write them down and call Social Security or Medicare before your enrollment period starts. It is better to ask now than to miss your window and pay a penalty later.

Frequently Asked Questions

What if I turn 65 in the middle of the month?

Your Initial Enrollment Period is based on the month you turn 65, not the specific day. If you turn 65 on June 15, your enrollment period still runs from March through September. You can sign up anytime during those seven months, and your coverage can start on the first day of your birthday month if you enroll early enough.

Can I sign up for Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before your 65th birthday, so you can sign up as early as then. Many people sign up in the first month of their enrollment period to make sure their coverage starts on time. You cannot sign up before that three-month window opens.

Do I have to sign up for Part B if I am still working?

If your employer has 20 or more employees, you can delay Part B without a penalty as long as you are covered by the employer plan. Once you stop working or lose that coverage, you have eight months to sign up for Part B. If you wait longer than eight months, you will pay a permanent penalty.

What if I did not get a notice from Social Security about Medicare?

Social Security mails notices three months before your 65th birthday, but mail can be delayed or lost. Do not wait for the notice. Call Social Security at 1-800-772-1213 to confirm your enrollment dates. You can also create an account on ssa.gov to see your information online.

Can the penalty be removed if I sign up late?

The penalty cannot be removed unless you can prove you had creditable coverage (employer or union insurance) during the time you delayed. If you did not have that coverage, the penalty is permanent. This is why it is important to sign up during your Initial Enrollment Period or to report employer coverage to Medicare if you have it.