Medicare has three main sign-up windows, and missing them can cost you in penalties for the rest of your life

You can sign up for Medicare during your Initial Enrollment Period, which is the seven-month window that includes the month you turn 65, the three months before, and the three months after. If you miss this window, you can still sign up during the General Enrollment Period from January 1 to March 31 each year — but you will pay a permanent penalty on your monthly premium for every month you delayed. There are also Special Enrollment Periods that open if you lose job-based coverage or move to a new state, and these do not carry penalties.

The rules are different if you are still working and covered by your employer's health plan. If your employer has 20 or more employees, you can delay Medicare without penalty as long as you are actively employed and covered. Once you leave that job or lose the coverage, you have eight months to sign up without a penalty.

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.
  • If you miss your Initial Enrollment Period and do not have a may have access to reason, you will pay a permanent 10 percent penalty on your Part B premium for every year you are enrolled in Medicare.
  • If you are still working and covered by an employer plan with 20 or more employees, you can delay Medicare without penalty until you leave that job.
  • Special Enrollment Periods open when you lose job-based coverage or move states, and these do not carry late-enrollment penalties.
  • 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 around age 65

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your window opens in March and closes in September. During this time, you can sign up for Medicare Part A (hospital insurance) and Part B (medical insurance) without any penalty, regardless of your health or medical history.

Part A is usually free if you or your spouse paid Medicare taxes while working. Part B requires a monthly premium, which changes each year. You should sign up even if you do not plan to use Medicare right away, because the penalty for missing Part B can add up quickly. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not enrolled.

If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty. This is called creditable coverage. You will need to tell Medicare that you have this coverage when you sign up for Part A, so the system knows not to charge you a penalty later.

General Enrollment Period: January 1 to March 31 each year

If you miss your Initial Enrollment Period, you can sign up during the General Enrollment Period, which runs from January 1 to March 31 every year. Coverage begins on July 1 of that year. However, signing up this way means you will pay a late-enrollment penalty.

The Part B penalty is 10 percent of the standard monthly premium for each full 12-month period you were may be able to access but not enrolled. This penalty is permanent — it stays on your premium for as long as you are in Medicare. For example, if you were may be able to access for two years before signing up, your premium will be 20 percent higher than the standard amount, and that extra cost never goes away.

There is also a penalty for Part D (prescription drug coverage) if you go without it for more than 63 days in a row. The penalty is about 1 percent of the national average Part D premium for each month you were without coverage, and it also lasts for the rest of your time in Medicare.

Special Enrollment Periods: When you can sign up without a penalty

You may may have access to for a Special Enrollment Period if you lose your job-based health coverage, move to a new state, or have a change in your life that affects your coverage. Common may have access to events include losing employer coverage when you retire, losing Medicaid, or moving outside your current plan's service area.

If you lose job-based coverage, you have eight months from the date your coverage ends to sign up for Medicare without a penalty. This is one of the most important exceptions to the penalty rules. You will need to show proof that you had the coverage — usually a letter from your employer or former employer stating when your coverage ended.

If you move to a new state, you may have a Special Enrollment Period to change your Medicare plan. The timing depends on whether you are moving into or out of your current plan's service area. Contact Medicare to confirm whether your move qualifies.

Still working? You may be able to delay Medicare

If you are still working and your employer offers health insurance, you can delay signing up for Medicare Part B without penalty as long as your employer has 20 or more employees. This rule applies even after you turn 65. You must be actively employed and actually covered by the plan — just being offered coverage is not enough.

When you eventually leave your job or lose the coverage, you have eight months to sign up for Part B without a penalty. This eight-month window is your Special Enrollment Period. You will need to provide proof that you had employer coverage, such as a letter from your employer stating the dates you were covered.

If your employer has fewer than 20 employees, the penalty rules are different. You should sign up for Medicare when you turn 65, even if you are still working and covered by the employer plan. Contact Medicare to discuss your specific situation.

How to sign up for Medicare

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. The Social Security office is often the easiest route if you have questions or need help with paperwork.

When you sign up, 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 job-based coverage, have that employer coverage information ready so you can tell Medicare about it.

You can sign up at any time during your Initial Enrollment Period, but do not wait until the last month. If you sign up in the last month of your window, your coverage may not start until the following month, which could leave you without coverage for a short time.

What happens if you miss the important date

If you miss your Initial Enrollment Period and do not have a may have access to reason for a Special Enrollment Period, you will have to wait until the next General Enrollment Period (January 1 to March 31) to sign up. Your coverage will not start until July 1 of that year, which could mean several months without Medicare coverage.

During those months without coverage, you are responsible for all medical costs. You will also owe the late-enrollment penalty on your Part B premium for the rest of your life in Medicare. The only way to avoid the penalty is to show that you had creditable coverage (such as job-based insurance or Medicaid) during the time you were not enrolled in Medicare.

If you believe you have a good reason for missing your important date — such as a serious illness or a mistake by Social Security — you can ask Medicare to reconsider. Contact 1-800-MEDICARE to discuss your situation. Medicare has some flexibility in rare cases, but you must ask within a specific timeframe.

Frequently Asked Questions

What if I turn 65 while I am still working?

You can delay Part B without penalty if your employer has 20 or more employees and you are covered by their health plan. You must sign up for Part A, but you can delay Part B. When you leave your job, you have eight months to sign up for Part B without a penalty.

Can I change my mind after I sign up?

Yes. You have seven months from the month you first enroll to change your coverage. This is called the Initial Coverage Election Period. After that, you can only change plans during the Annual Enrollment Period from October 15 to December 7 each year.

Do I have to sign up for Part D when I sign up for Medicare?

Part D is optional, but if you go without it for more than 63 days in a row, you will pay a penalty for the rest of your time in Medicare. If you do not take prescription drugs, you can skip Part D, but sign up later if your situation changes.

What if I am not a U.S. citizen?

You can sign up for Medicare if you are a 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 legal residency status when you sign up.

How do I know if my employer coverage counts as creditable coverage?

Ask your employer's benefits department whether your plan is creditable for Medicare purposes. They should be able to tell you or provide a letter stating that it is. If you are unsure, contact Medicare at 1-800-MEDICARE and have your employer plan information ready.