What is Medicare Part B?

Medicare Part B is the category of Medicare health insurance coverage that includes outpatient medical services, doctor services, medical equipment and supplies, preventive care, and limited home health services. To be eligible for Medicare Part B, one must be a U.S. citizen, or permanent legal resident of more than five continuous years, aged 65 or over. It’s possible to qualify for Medicare when you’re younger than 65 if you’re receiving Social Security or Railroad Retirement Board disability benefits; see details about Medicare eligibility.

Most beneficiaries are automatically enrolled in Medicare Part B when they become eligible. Those who are not automatically enrolled must apply through the Social Security Administration (or Railroad Retirement Board, if applicable) for Part B coverage.

Most Medicare Part B covered services require you to pay 20% of the Medicare-approved amount for the service. Other Medicare-covered services are free of charge – for example, you typically don’t pay for one flu shot per year. Still other Medicare-covered services may have different costs.

Medicare Part B coverage generally requires that the health-care provider delivering the service accept Medicare assignment. This means that the provider has agreed to accept the Medicare-approved amount as payment in full, and won’t charge you any more for the service (besides the Part B coinsurance or copayment and the deductible, if applicable). If a provider doesn’t accept Medicare assignment, you could have to pay more for the service. In most cases, you’re not required to pay more than 15% more than the Medicare-approved amount.

What does Medicare Part B cover?

Medicare Part B covers many important medical services, items, and supplies. Some of them are listed below (this is not a complete list). Note that these services must come from providers who accept Medicare assignment.

  • One “Welcome to Medicare” physical exam
  • Annual wellness exams
  • Diagnostic tests, lab work, and screenings when ordered by your doctor
  • Doctor services
  • Ambulance services (generally by ground transportation to the nearest medical facility that’s appropriate for your medical emergency)
  • Skilled nursing services (when your doctor determines they’re medically necessary; usually these services are covered for a limited time)
  • Chemotherapy
  • Limited physical and occupational therapy when your doctor determines they’re medically necessary
  • Speech-language pathology when your doctor determines it’s medically necessary
  • Certain diabetic supplies prescribed by your doctor
  • Flu and pneumonia vaccinations
  • Durable medical equipment (such as wheelchairs and walkers) that your doctor determines are medically necessary
  • Some mammography and Pap smear screening

It’s important to be aware of some common health services and items Medicare Part B does not cover, such as:

  • Prescription drugs (that are not administered to you by a physician)
  • Routine foot care
  • Alternative care such as acupuncture
  • Long-term custodial care, such as help with daily activities
  • Routine eye examinations and eyeglasses in most situations
  • Hearing aids

Medicare Part B costs

Your main costs associated with Medicare Part B are the monthly premium, the annual deductible, and the coinsurance and copayment amounts for Medicare-covered services mentioned above.

The monthly premium for Medicare Part B can change annually. In 2021, the standard Part B premium is $148.50.

2021 Medicare Part B monthly premiums (based on your 2019 annual income)
If you file an individual tax return and your income was:


If you file a joint tax return and your income was:


You pay
$88,000 and less $176,000 and less $148.50
$88,001-$111,000 $176,001-$222,000 $207.90
$111,001-$138,000 $222,001-$276,000 $297.00
$138,001-$165,000 $276,001-$330,000 $386.10
Above $165,000 and less than $500,000 Above $330,000 and less than $750,000 $475.20
$500,000 and above $750,000 and above $504.90
Source: Medicare.gov
If you’re married but file a separate tax return from your spouse, and your annual income in 2019 was:


You pay
$88,000 or less $148.50
Above $88,000 and less than $412,000 $475.20
$412,000 and above $504.90
Source: Medicare.gov

Before Medicare Part B pays its share toward most covered services and items, you need to pay the annual deductible. In 2021, this deductible is $203. The deductible doesn’t apply to every covered service. After you pay your deductible, you’ll pay 20% of the Medicare-approved amount for most Medicare-covered services.

Delaying enrollment in Medicare Part B

Because Medicare Part B comes with a monthly premium, some beneficiaries delay enrollment – for example, if they’re covered through an employer-based health plan. If you decide to delay Part B enrollment, you may want to:

  • Check with your current health plan administrator for details about your plan coverage and how the plan works with Medicare.
  • Decline Part B enrollment during your Initial Enrollment Period (when you’re first eligible for Medicare) to avoid paying any Part B premium. If you qualify for automatic enrollment, as many beneficiaries do, you need to decline Part B enrollment manually.
  • Be aware that enrollment in Medicare Part B (along with Part A) is required if you want to sign up for a Medicare Advantage plan or a Medicare Supplement
  • Be aware that if you decide to sign up for Part B later on (after your Initial Enrollment Period), you could have to pay a Part B late-enrollment penalty unless you sign up during a Medicare Part B Special Enrollment Period. Here’s an example of how the Special Enrollment Period works. If your employer-based health insurance will end soon, you can sign up for Part B before the other coverage ends. You can also sign up for Part B during the 8-month period after the month that the employer-based coverage ends, or employment ends – whichever happens first. In most cases, you won’t have to pay the Part B late-enrollment penalty as long as you sign up during a Special Enrollment Period.

Remember that Medicare Part B doesn’t cover your prescriptions in most situations. If you’re enrolled in Medicare Part A or Part B, you can sign up for prescription drug coverage under Medicare Part D. Read about Medicare Prescription Drug Plans.