Part B enrollment windows depend on when you turn 65 and whether you have other health coverage

You can sign up for Medicare Part B during three main periods: your Initial Enrollment Period (IEP), the General Enrollment Period (GEP), or a Special Enrollment Period (SEP) if you meet certain conditions. Most people have a seven-month window centered on the month they turn 65. If you miss that window and do not have a may have access to reason, you will pay a permanent penalty on your Part B premium for as long as you have Medicare.

The exact dates you can sign up matter because late enrollment penalties are real and they do not go away. Understanding which window applies to you now prevents a costly mistake later.

Key Takeaways

  • Your Initial Enrollment Period is a seven-month window: three months before the month you turn 65, the month you turn 65, and three months after.
  • If you have health coverage through a current job or a spouse's current job, you can delay Part B without penalty as long as that coverage continues.
  • The General Enrollment Period runs January 1 through March 31 each year, but you pay a penalty if you enroll then instead of during your Initial Enrollment Period.
  • Late enrollment penalties add 10 percent to your Part B premium for each full year you could have had it but did not, and the penalty is permanent.
  • You must contact Medicare directly or use Medicare.gov to enroll; your doctor's office and health insurance broker cannot do it for you.

Your Initial Enrollment Period: the seven-month window

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. This is your main chance to sign up for Part B without penalty. For example, if you turn 65 in June, your IEP runs from March through September.

You can enroll any time during those seven months. You do not have to wait until the month you turn 65. Many people sign up in the month before they turn 65 so coverage begins on the first day of the month they turn 65. If you enroll after that month, your coverage will start the first day of the following month.

The IEP is the only enrollment window where you can avoid a lifetime penalty. If you miss it and do not have a may have access to reason, the penalty applies permanently.

When you can delay Part B without penalty

You can postpone Part B past your Initial Enrollment Period without penalty if you have health coverage through a current job — either your own job or your spouse's job. This coverage must be active employment-based insurance, not retiree coverage or COBRA. As long as you are still working and covered, you can wait to enroll in Part B.

When you leave that job or the coverage ends, you have a Special Enrollment Period of eight months to sign up for Part B without penalty. This eight-month window starts the month after your job-based coverage ends. You will need to show proof that you had job-based coverage — usually a letter from your employer or health plan stating the coverage dates and that it was based on current employment.

If you have coverage through Medicare Advantage or Original Medicare already, you do not get a Special Enrollment Period for Part B. The delay-without-penalty rule applies only to job-based coverage.

The General Enrollment Period and late penalties

If you miss your Initial Enrollment Period and do not have a may have access to reason, you can still sign up during the General Enrollment Period, which runs January 1 through March 31 each year. However, you will owe a permanent penalty on your Part B premium.

The penalty is 10 percent of the standard Part B premium for each full year you could have had Part B but did not. If you were may be able to access for three years and did not enroll, your penalty is 30 percent of the standard premium. This penalty stays with you for life, even if you move to a different state or change plans.

Coverage that starts through the General Enrollment Period begins July 1 of that year. So if you enroll in February, you will not have coverage until July.

Special Enrollment Periods for specific situations

A Special Enrollment Period lets you sign up outside the normal windows without penalty if you meet certain conditions. The most common reason is losing job-based coverage, but there are others.

You may have a Special Enrollment Period if you move out of your health plan's service area, if your plan leaves Medicare, if you are a U.S. citizen or national living abroad and return to the United States, or if you are a Native American or Alaska Native. Each situation has its own enrollment window — usually 60 days to eight months depending on the reason. You will need to provide proof of the may have access to event, such as a notice from your health plan or a letter from your employer.

Contact Medicare directly to find out whether your situation qualifies and what documents you need to bring.

How to sign up for Part B

You can enroll in Part B through three channels: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office.

Online enrollment through Medicare.gov is usually the fastest. You will need your Social Security number, date of birth, and citizenship or immigration status. The process takes about 10 minutes. You can enroll any day of the week.

By phone, a Medicare representative will walk you through the same questions. Wait times vary, but calling early in the week or early in the day often means shorter holds. In person, bring your Social Security card, proof of citizenship or legal residency, and proof of age. Social Security offices are open Monday through Friday, and some locations take appointments online.

You cannot enroll through your doctor's office, your current health insurance broker, or a Medicare Advantage plan. Those organizations can answer questions, but only Medicare can process your Part B enrollment.

What happens after you enroll

After you submit your enrollment, Medicare will send you a confirmation letter within two weeks. This letter shows your coverage start date and your Part B premium amount. Keep this letter — you will need it to prove your enrollment date if there is ever a question about penalties.

Your Part B coverage will begin on the first day of the month you enroll, or the first day of the following month if you enroll after the 15th. Your Medicare card will arrive separately, usually within two weeks of your coverage start date.

Your Part B premium is deducted from your Social Security check each month, unless you choose to pay Medicare directly. If you do not receive Social Security yet, Medicare will bill you monthly.

Frequently Asked Questions

What if I turn 65 while I am still working?

You can delay Part B without penalty as long as you have health coverage through your current job. When you leave that job, you have eight months to enroll in Part B without penalty. You must show proof that your job-based coverage has ended.

Can I enroll in Part B after I turn 65 if I missed my Initial Enrollment Period?

Yes, but only during the General Enrollment Period (January 1 through March 31 each year), and you will owe a permanent penalty on your premium. The penalty is 10 percent per year you could have had Part B but did not. Coverage starts July 1 if you enroll during the General Enrollment Period.

Do I have to enroll in Part B if I have a Medicare Advantage plan?

No. If you are already enrolled in Medicare Part A and Part B together, you can choose a Medicare Advantage plan instead. But you cannot have just Part A without Part B — they are a package. If you have only Part A, you must enroll in Part B during your Initial Enrollment Period or face a penalty.

What if my employer says I do not need Part B because they cover retirees?

Retiree coverage is not the same as job-based coverage for active employees. If you are retired, you do not have a reason to delay Part B. You must enroll during your Initial Enrollment Period or pay a penalty. Check with your employer's benefits office to confirm whether your coverage is retiree coverage or active employment coverage.

Can I change my mind after I enroll in Part B?

Yes, but only during certain windows. If you enroll and then change your mind within 12 months, you can disenroll, but only if you have other coverage. You cannot straightforward drop Part B and go without it. If you disenroll and later want Part B again, you will owe a penalty unless you have a may have access to reason.