Medicare Part B covers doctor visits, outpatient care, and medical equipment — but you have to sign up for it separately from Part A, and the window to do so without a penalty is limited.

Part B is not automatic. When you turn 65, you get Part A (hospital insurance) without doing anything if you are already getting Social Security. Part B (medical insurance) requires you to take action during your Initial Enrollment Period, which runs from three months before your 65th birthday through three months after the month you turn 65 — a seven-month window total.

If you miss that window and do not have other coverage that counts as "creditable," you will pay a permanent 10 percent surcharge on your Part B premium for every 12 months you were may be able to access but not enrolled. That penalty stays with you for life, so the cost of waiting is real.

You can sign up through Social Security, Medicare directly, or your local Social Security office. The process takes about 15 minutes if you have your information ready.

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 — missing it triggers a permanent premium increase.
  • You sign up through Social Security online, by phone at 1-800-772-1213, or in person at your local Social Security office.
  • You will need your Social Security number, birth date, citizenship or immigration status, and information about any current health coverage.
  • Part B does not start the month you sign up; it starts the first day of the month after you sign up, or the first day of the month you turn 65 if you sign up during your Initial Enrollment Period.
  • If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty — but you must tell Social Security about your coverage.

When Your Initial Enrollment Period Starts and Ends

Your seven-month window opens three months before the month you turn 65. If you turn 65 in June, your period begins in March. It closes three months after the month you turn 65 — so if you turn 65 in June, you can sign up through September.

The exact dates matter because Medicare counts months, not days. If you turn 65 on June 15, you still have until September 30 to sign up without penalty. If you sign up in June, your coverage starts July 1. If you sign up in July, your coverage starts August 1. If you sign up in September, your coverage starts October 1.

After September 30, you enter what Medicare calls the General Enrollment Period, which runs January 1 through March 31 each year. You can sign up then, but your coverage will not start until July 1 of that year, and you will owe the 10 percent surcharge on your premium.

How to Sign Up Online or by Phone

The fastest route is the Social Security website at ssa.gov. Log in to your "my Social Security" account, go to "Medicare," and follow the prompts to sign up for Part B. The whole process takes about 10 to 15 minutes. You will need your Social Security number, date of birth, and citizenship or immigration status.

If you do not have a my Social Security account, you can create one on the same website. You will need an email address and a phone number. If you prefer not to use the website, call Social Security at 1-800-772-1213. The line is open Monday through Friday, 7 a.m. to 7 p.m. Eastern time. Have your Social Security number and date of birth ready.

You can also walk into your local Social Security office with your Social Security card, proof of citizenship or immigration status (passport, birth certificate, or green card), and proof of age (driver's license or passport). Bring proof of any current health coverage if you have it. The office will complete your sign-up on the spot.

What Information You Need Before You Start

Gather these documents before you sign up: your Social Security number, your date of birth, your citizenship or immigration status, and the name and phone number of any current health insurance you have (employer coverage, TRICARE, Veterans benefits, or other Medicare coverage). If you are signing up in person, bring your Social Security card and a photo ID.

If you are still working and covered by your employer's health plan, tell Social Security about it. This is important: if your employer has 20 or more employees, you may be able to delay Part B without penalty. Social Security will ask for your employer's name and the date your coverage started. Write down the answers before you call or visit.

If you are a federal employee or railroad retiree, you may have different rules. Have your employee ID or retirement documents handy so you can answer questions about your coverage type.

What Happens After You Sign Up

Social Security will send you a confirmation letter in the mail within two weeks. Keep this letter — it shows your Part B start date and your premium amount. Your Medicare card will arrive separately, usually within two weeks as well, though it can take up to four weeks.

Your Part B premium is deducted from your Social Security check each month, unless you are not yet receiving Social Security. If you are not yet on Social Security, Medicare will send you a bill. The standard premium in 2024 is $164.90 per month, but it changes each year and may be higher if your income is above a certain threshold.

Once your Part B is active, you can start using it right away. Show your Medicare card to your doctor, hospital, or other provider. They will bill Medicare directly for covered services.

If You Missed Your Initial Enrollment Period

If your seven-month window has closed and you do not have other may have access to coverage, you can still sign up, but you will face consequences. You can sign up during the General Enrollment Period (January 1 through March 31 each year), and your coverage will start July 1. You will also pay a 10 percent surcharge on your Part B premium for every 12 months you were may be able to access but not enrolled.

There are exceptions. If you have coverage through your current employer (and your employer has 20 or more employees), you can sign up without penalty during an eight-month window that starts when you leave that job or your coverage ends. You must sign up within that eight-month period. If you have TRICARE or Veterans benefits, different rules explore — contact your benefits administrator to confirm your enrollment window.

If you missed your important date and are unsure whether you may have access to for an exception, call Social Security at 1-800-772-1213 and explain your situation. They can tell you whether you owe a surcharge and when you can sign up next.

Part B Costs and What It Covers

Part B has two costs: a monthly premium and a yearly deductible. The standard monthly premium is $164.90 in 2024, but it increases each year and may be higher if your income is above $97,000 (single) or $194,000 (married filing jointly). If your income is higher, you will pay an additional surcharge called an Income-Related Monthly Adjustment Amount (IRMAA).

The yearly deductible is $240 in 2024. After you meet your deductible, you typically pay 20 percent of the cost of covered services, and Medicare pays 80 percent. Part B covers doctor visits, outpatient surgery, diagnostic tests, mental health services, and durable medical equipment like wheelchairs and oxygen.

Part B does not cover dental, vision, or hearing care. If you want coverage for those services, you will need to buy a separate Medigap or Medicare Advantage plan.

Frequently Asked Questions

What if I am still working at 65 — do I have to sign up for Part B?

Not when ready, if your employer has 20 or more employees and you are covered by their health plan. You can delay Part B without penalty as long as you are actively employed and covered. When you leave your job or your coverage ends, you have eight months to sign up for Part B without penalty. Tell Social Security about your employer coverage when you do sign up.

Can I sign up for Part B before I turn 65?

Yes. Your Initial Enrollment Period begins three months before the month you turn 65. You can sign up online, by phone, or in person at your local Social Security office during that time. If you sign up before you turn 65, your coverage will start the first day of the month you turn 65.

What if I have Medicare Advantage — do I need Part B?

Yes. Medicare Advantage (Part C) is a way to receive your Part A and Part B benefits through a private insurance company, but you must be enrolled in both Part A and Part B to join a Medicare Advantage plan. You sign up for Part B first, then choose your Medicare Advantage plan during the Annual Enrollment Period (October 15 through December 7).

How much will my Part B premium be?

The standard premium is $164.90 per month in 2024, but it changes each year. If your income is above $97,000 (single) or $194,000 (married filing jointly), you will pay more. Social Security will tell you your exact premium amount when you sign up, and it will appear on your confirmation letter.

What if I sign up late but have other health coverage — do I still owe the penalty?

It depends on the type of coverage. If you have coverage through an employer with 20 or more employees, TRICARE, or Veterans benefits, you may not owe a penalty. If you have individual health insurance or coverage from an employer with fewer than 20 employees, you will owe the surcharge. Call Social Security to confirm your situation.