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What is Medicare Part B?

By August 26, 2020December 30th, 2022Health Insurance Medicare
Hands on a desk of a doctor and patient

Original Medicare has two parts: Part A (hospital insurance) and Part B (medical insurance). The Part B portion covers two types of medical services — preventive services and medically-necessary services — when provided by doctors and providers who accept Medicare.

  • Preventive services help prevent illness (like the flu) or detect it at an early stage.
  • Medically-necessary services (or supplies) diagnose or treat a medical condition.

What Medicare Part B covers

Some of what Part B covers includes doctors and providers’ services and outpatient care, as well as:

To find out if Medicare Part B covers a specific service or item, search the complete list of what Medicare covers.

Part B eligibility

Your Medicare Part B eligibility can be determined by your Medicare Part A premium:

  • If you have premium-free Part A, then you’re eligible for Part B.
  • If you pay a premium for Part A, then you must meet the following requirements to be eligible for Part B:
    Be age 65 or older and a U.S. resident
    AND be either:
    A U.S. citizen, OR
    An alien who has been lawfully admitted for permanent residence and has been residing in the U.S. for five continuous years before the month of applying for Medicare

If you have not yet enrolled in Part A or don’t know your premium amount, you can use the eligibility tool to find out if you are eligible for Medicare Part B.

Enrolling in Medicare Part B

Some people are enrolled in Part B automatically, while others must sign up for it on their own.

Automatic enrollment in Part B

You will be enrolled in Medicare Part B automatically if:

  • You are already getting benefits from Social Security
  • You are younger than 65 and are receiving Social Security Disability Insurance (SSDI)
  • You have amyotrophic lateral sclerosis (ALS) or End Stage Renal Disease (ESRD)

If you were automatically enrolled in Medicare Part B and would like to drop it, contact Social Security for instructions on how to submit a signed request.

Self-enrollment in Part B

If you would like Part B coverage, and you weren’t automatically enrolled, you should sign up for it during your seven-month Initial Enrollment Period (IEP). Your IEP starts three months before the month you become eligible, includes the month of your birthday, and ends three months after the month you became eligible. If you miss your IEP, there are other opportunities during the year when you can enroll.

If you work past 65 and have creditable health coverage through your employer (with more than 20 employees), you can delay enrolling in Part B (without penalty) until your employer coverage ends.

How to apply for Part B

You can enroll in Medicare Part B by contacting the Social Security Administration at or 1-800-772-1213 (TTY: 1-800-325-0778).

Part B late enrollment penalty

Though enrollment in Medicare Part B is optional, be warned. If you don’t sign up for Part B when you’re first eligible and decide you want to enroll later, you may have to pay a 10 percent late penalty for each 12-month period you delayed enrolling. In most cases, you will pay this penalty for as long as you have Part B coverage.

Example: If Roy’s monthly Part B premium is $100, but he enrolls one year late, there may be a $10 late penalty added to his premium. If he delays for two years, the late penalty may be $20, and if he waits three years, he may pay an additional $30 a month.

Medicare Part B premium and out-of-pocket costs

Medicare Part B is not free. It is available for a monthly premium based upon your income level, and the monthly premium may change from year to year. You can choose to have your premium deducted from your monthly Social Security check, or you can choose to be billed. In 2020, the standard Part B premium was $144.60. The eligibility tool can help calculate your premium.

Part B also has an annual deductible and coinsurance for the services you receive. This means after you have met your initial deductible, Medicare will pay a certain percentage of your bill, while you pay the remainder.

Learn more about how Medicare works. Visit

Website Last Updated: 06/23/20

Material ID: Y0041_HM_87872_2020

Theresa Lauer

Theresa Lauer is the Director of Medicare Broker Sales for Independence Blue Cross. She is a long-time leader in cultivating, developing, managing, and leading profitable sales programs. In her current role, Theresa and her team forge new opportunities each day within the Independence five-county southeastern PA area.