Sign up for Medicare Part B during your Initial Enrollment Period or during General Enrollment

Your Initial Enrollment Period is a seven-month window that starts three months before the month you turn 65 and ends three months after. If you sign up during the first three months of this window, your Part B coverage begins the month you turn 65. If you sign up in the month you turn 65 or later in the window, there is a one- or two-month delay before coverage starts.

If you miss your Initial Enrollment Period, you can sign up during General Enrollment, which runs January 1 through March 31 each year. Coverage begins July 1 of that year. However, missing the important date usually means you will pay a higher monthly premium for Part B for as long as you have Medicare — a permanent penalty of about 10 percent per year you were late, though the exact amount depends on how many years passed.

There are exceptions: if you or your spouse were still working and had health insurance through an employer, you may have a special enrollment period that lets you sign up without penalty. You must sign up within eight months of losing that job-based coverage or retiring, whichever comes first.

Key Takeaways

  • Your Initial Enrollment Period is seven months long, centered on the month you turn 65, and is the only time you can sign up for Part B without a permanent premium penalty.
  • If you sign up in the first three months of your Initial Enrollment Period, Part B coverage starts the month you turn 65; later sign-ups have a one- or two-month delay.
  • General Enrollment runs January through March each year, but signing up then means a permanent increase to your Part B premium and a July start date.
  • If you had employer health insurance when you turned 65, you may have eight months after losing that coverage to sign up for Part B without penalty.
  • You sign up through Social Security, Medicare.gov, or by calling 1-800-MEDICARE.

How to find your Initial Enrollment Period dates

Your Initial Enrollment Period depends on your birth month. Count back three months from your birthday to find when the window opens, and count forward three months to find when it closes. For example, if you turn 65 in June, your Initial Enrollment Period runs from March through September.

Social Security will mail you a notice about Medicare a few months before you turn 65. That notice includes your exact enrollment dates. You can also log into your personal Social Security account at ssa.gov or call Social Security at 1-800-772-1213 to confirm the dates.

Where to sign up for Part B

You have three main routes. The first is Social Security: you can visit your local Social Security office, call 1-800-772-1213, or go online to ssa.gov. Social Security handles Medicare sign-ups as part of the retirement process.

The second is Medicare.gov: go to the website, log in or create an account, and follow the sign-up steps. You can also call 1-800-MEDICARE (1-800-633-4227) and speak to someone who can walk you through it over the phone.

The third is to visit or call your local Social Security office in person. Bring your Social Security card and proof of citizenship or legal residency. If you are signing up late and want to ask about exceptions to the penalty, an in-person visit often gives you the chance to explain your situation to someone who can review it.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your Initial Enrollment Period and you do not have an exception, you will have to wait until the next General Enrollment period (January 1 through March 31). Your coverage will not start until July 1 of that year, meaning you could go without Part B for months.

More importantly, you will owe a permanent premium penalty. The penalty is roughly 10 percent of the standard Part B premium for each full year you were late. If you were two years late, for example, your premium would be about 20 percent higher than someone who signed up on time — and you will pay that higher amount for the rest of your life on Medicare.

The only way to avoid this penalty is to show that you had creditable coverage (health insurance through an employer or union) when you turned 65 and for the entire time you were not signed up for Part B. You must provide proof of that coverage to Medicare.

Special enrollment if you had employer coverage

If you or your spouse were still working and had health insurance through your job when you turned 65, you do not have to sign up for Part B right away. You have an eight-month window after you or your spouse stops working or retires, whichever comes first. During this window, you can sign up for Part B without paying the late penalty.

To use this exception, you must tell Medicare that you had employer coverage. When you sign up, have your employer's health plan documents ready — Medicare will ask for proof. The eight-month clock starts the month after you lose the coverage or retire, so mark that date and count forward.

This exception is common for people who work past 65 or whose spouses are still working. If this describes your situation, do not assume you have to sign up at 65 — but do sign up before the eight months are up, or you will face the penalty.

What Part B costs and covers

Part B has a monthly premium, which changes each year. In 2024, the standard premium is $164.90 per month, but higher-income beneficiaries pay more. You also pay a yearly deductible (currently $240) and 20 percent of the cost of most services after that.

Part B covers doctor visits, outpatient hospital care, medical equipment, and preventive services like screenings and vaccines. It does not cover hospital stays (that is Part A), prescription drugs (that is Part D), or long-term care. Many people sign up for a Medigap or Medicare Advantage plan to cover the costs Part B does not.

Frequently Asked Questions

What if I turn 65 but I am not ready to retire yet?

You can delay signing up for Part B if you or your spouse have health insurance through your job. You have eight months after you stop working or retire to sign up without penalty. If you keep working and keep your employer coverage, you do not have to sign up at 65.

Can I sign up for Part B online?

Yes. Go to Medicare.gov, create or log into your account, and follow the sign-up steps. You can also call 1-800-MEDICARE to sign up over the phone with someone's help, or visit your local Social Security office in person.

What if I missed my Initial Enrollment Period and I do not have employer coverage?

You can sign up during General Enrollment (January 1 through March 31), and coverage will start July 1. However, you will pay a permanent premium penalty of about 10 percent per year you were late. Contact Medicare to ask if any exceptions explore to your situation.

Do I have to sign up for Part B if I have a Medicare Advantage plan?

Yes. Medicare Advantage (Part C) requires you to have both Part A and Part B. You sign up for Part B during your Initial Enrollment Period, and then you can enroll in a Medicare Advantage plan during the annual enrollment period (October 15 through December 7).

What if I am still working at 65 and have not signed up for Part B yet?

If you have employer health insurance through your job, you can wait to sign up. You have eight months after you stop working or retire to sign up without penalty. Keep track of when you lose that coverage so you know your important date.