Medicare Part B: What Does it Cover?

Medicare Part B covers medically necessary services and supplies not covered by Medicare Part A. This optional plan requires a premium.

Medicare Part B generally includes:

  • Outpatient care
  • Ambulance services
  • Durable medical equipment
  • Preventive care, like flu shots and certain screenings
  • Part-time or intermittent home health and rehabilitative care (if medically necessary)

You can enroll in Medicare Part B through the federal government at the same time you enroll in Medicare Part A. Some private insurers, like Medical Mutual, offer Medicare Advantage plans, which combine your Part A and Part B benefits. However, you must still enroll in Part A and Part B first and continue to pay your Part B premium.

Learn more about Medicare Advantage plans from Medical Mutual.

Part B Eligibility

Individuals entitled to premium-free Part A are eligible and automatically enrolled in Part B.  If you don’t qualify for premium-free Medicare Part A, you can still enroll in Medicare Part B if you meet both of these criteria:

  • You are 65 years or older
  • You are a citizen or permanent resident of the U.S.

If you are under age 65, you may also be eligible for automatic enrollment if:

  • You are receiving Social Security or Railroad Retirement Board (RRB) disability benefits
  • You have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS)

Medicare Part B Enrollment

Individuals who are not eligible for automatic Part B enrollment, or who previously refused Part B must sign up for Medicare Part B manually (unless you are under age 65 and receiving retirement benefits or if you qualify for Medicare through disability). You have three enrollment periods.

Initial Enrollment Period

Your Initial Enrollment Period lasts for seven months and includes:

  • Three months before your 65th birthday
  • The month you turn 65
  • The three months after your birthday

Medicare Part B requires you to pay a premium, so you may want to delay enrollment if you have health coverage through your employer. Coverage through an employer-sponsored plan (with more than 20 employees) excludes you from late enrollment penalties when you enroll in Part B after the Initial Enrollment Period passes.

To enroll in Medicare Part B, you need to contact the Social Security Administration. You do so by going to the Social Security website, visiting your local Social Security office or calling 1-800-772-1213 (TTY users dial 1-800-0778), Monday through Friday, from 7:00 a.m. to 7:00 p.m.

General Enrollment Period

You can always sign up for Medicare Part B during the General Enrollment Period, which runs from Jan. 1 to March 31 each year. However, you may have to pay a late enrollment penalty if you wait until this time to sign up instead of during your Initial Enrollment Period.

Special Enrollment Period

Most people have to pay a premium for Medicare Part B. If you are currently covered through your or your spouse’s employer, you might want to delay your Medicare Part B enrollment. You can check with your benefits administrator to see how your insurance would work with Medicare.

You can still enroll later during the Special Enrollment Period without paying a late penalty. This eight-month period begins immediately after your health coverage or employment ends – whichever occurs first. Even if you have COBRA coverage, you still need to enroll right after your employer coverage ends to qualify for the Special Enrollment Period.

Part B Premiums

The premium for most Medicare Part B beneficiaries is available at People with incomes above a certain amount may pay more. Premiums also change from year to year.

Deductibles and Coinsurance

The annual deductible for Medicare Part B beneficiaries is available at You are also responsible for paying 20% coinsurance.

If your doctor or healthcare provider accepts Medicare’s payment for a covered service, you pay the deductible plus 20% of the Medicare-approved amount for services rendered. Your doctor cannot charge you more than the Medicare-approved amount, but you are still responsible for cost-sharing.