What is Medicare Part B?

Updated on December 21st, 2021

Reviewed by Diane Omdahl

We aim to help you make informed healthcare decisions. While this post may contain links to lead generation forms, this won’t influence our writing. We follow strict editorial standards to give you the most accurate and unbiased information.

Original Medicare Part B medical insurance covers medically necessary services to diagnose or treat a medical condition, and preventive services, such as yearly wellness visits, flu vaccines and colonoscopies. 

What Does Medicare Part B Medical Insurance Cover?

Medicare Part B covers services like:1

  • Physician visits.
  • Diagnostic tests.
  • Preventive services.
    • Mammograms.
    • Colorectal cancer screenings.
    • Diabetes screenings. 
    • Depression screenings.
    • Prostate cancer screenings
    • Shots (flu, Hepatitis B, Pneumococcal)
    • Alcohol misuse screenings and counseling
    • Tobacco use cessation counseling
  • Outpatient medical services.
  • Outpatient therapy services.
    • Occupational therapy.
    • Physical therapy.
    • Speech-language pathology services. 
    • Some chiropractic services
  • Telehealth.
  • Ambulance services: When you need to be transported to a hospital, critical access hospital, or skilled nursing facility for medically necessary services, and transportation in any other vehicle could endanger your health.
  • Durable medical equipment (DME): If your doctor prescribes it for use in your home, including blood sugar monitors, crutches, walkers and hospital beds. 
  • Outpatient mental health
    • Outpatient: Medicare Part B covers some outpatient services, such as depression screenings, individual and group psychotherapy, and family counseling, among other things
    • Partial hospitalization: Part B may cover partial hospitalization if you meet certain requirements and your doctor certifies that you’d otherwise need inpatient treatment.
  • Limited outpatient prescription drugs: Part B covers some outpatient prescription drugs, typically those you wouldn’t give to yourself or must get in a medical setting, such as injectable osteoporosis drugs. 
  • Clinical research: Part B covers some costs, like office visits and tests, and the necessary services if you’re part of a qualified research study. 

What Doesn’t Medicare Part B cover?

Original Medicare Part B doesn’t cover everything.2 Some things that aren’t covered by Medicare include: 

  • Long-term care (also called custodial care).
  • Most dental care.
  • Eye exams related to prescribing glasses.
  • Dentures.
  • Cosmetic surgery.
  • Acupuncture (unless it’s for chronic lower back pain).
  • Hearing aids and exams for fitting them.
  • Routine foot care.

If you’re wondering whether a test or service is covered by Medicare, you can check here

Who’s eligible for Medicare Part B?

Anyone who’s eligible for Medicare is eligible for Part B, and that’s anyone who is 65 or older, younger people with disabilities who have been receiving Social Security disability insurance (SSDI) benefits for 24 months and people with end-stage renal disease.3 Also, anyone who has Amyotrophic Lateral Sclerosis (ALS) or Lou Gehrig’s disease.

Considering a Medicare Advantage or Medicare Supplement Plan?

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If you’re not sure if you’re eligible, try Medicare’s eligibility tool

What Will Medicare Part B cost?

Medicare Part B requires a monthly premium,4 which will be automatically deducted from any benefit you’re receiving from Social Security, the Railroad Retirement Board or the Office of Personnel Management. Otherwise, you’ll get a bill.

You’ll generally pay a standard premium amount ($170.10/month in 2022) unless your modified adjusted gross income is over a certain amount. For this calculation, Medicare uses your IRS tax return from two years prior to identify whether you’re a higher-income beneficiary. If you are, you’ll pay an income-related monthly adjustment amount (IRMAA). Here’s how it works.

If your yearly income in 2020 (which affects your 2022 premiums) was:

File taxes as an individualFile taxes as married filing jointlyFile taxes as married, filing separatelyYou’ll pay each month in 2022*
$91,000 or less$182,000 or less$91,000 or less$170.10
Above $91,000 up to $114,000Above $182,000 up to $228,000Not applicable$238.10 
Above $114,000 up to $142,000Above $228,000 up to $284,000Not applicable$340.20 
Above $142,000 up to $170,000Above $284,000 up to $340,000Not applicable$442.30 
Above $170,000 up to $500,000Above $340,000 up to $750,000Above $91,000 up to $409,000$544.30 
$500,000 or above$750,000 or above$409,000 and above$578.30
*This amount includes the standard Part B premium plus any IRMAA. 

In addition to your monthly premiums, Medicare Part B has a deductible of $233 in 2022. Once you hit your deductible during the year, you’ll usually be responsible for 20% of Medicare charges for all Part B services (coinsurance). 

Although the costs above are standard, if you don’t enroll in Part B when you’re first eligible — and you didn’t have a valid reason to delay enrollment — your premium may go up 10% for each 12-month period you could’ve had it (but didn’t).5 In most cases, you’ll pay this late enrollment penalty for as long as you have Part B, so don’t miss your window. 

How Do You Sign Up for Medicare Part B? 

Signing up for Medicare Part B depends on your situation. In some cases, enrollment is automatic, and in others you must apply. If you’re already receiving benefits from Social Security or the Railroad Retirement Board (RRB) for at least four months before you turn 65, you’ll be automatically enrolled. If that’s not the case, you can apply online at ssa.gov/medicare.6 

That said, while most people should enroll in Medicare Part A, some people may choose to delay signing up for Part B. This typically depends on the kind of health coverage you have. For instance, if you’re working and you still have health coverage through a job, or you have coverage through your spouse who’s still working, you may be able to delay coverage without paying a late enrollment penalty.7 There are a lot of nuances — find out about those and other situations here

If you have Lou Gehrig’s disease (ALS), end-stage renal disease (ESRD), or you’re under 65 and you are receiving Social Security Disability Insurance (SSDI) benefits, find out about enrollment here

When Can You Sign Up?

Like Medicare Part A, typical Medicare Part B enrollment (when you’re 65) comes with a seven-month Initial Enrollment Period for signup. This includes the three months before and after the month you turn 65, plus the month of your birthday. Hence, if you turn 65 in April, your Initial Enrollment Period stretches from January through July.8 

If you aren’t automatically enrolled, you can sign up for Part B any time during your Initial Enrollment Period. But if you wait until the month you turn 65 (or any of the three months after it), your Part B coverage will be delayed by one to three months after enrollment. 

If you miss your initial signup and you aren’t eligible for a Special Enrollment Period (SEP), you can enroll in Part B during the General Enrollment Period, between January 1 and March 31 each year. There are a variety of reasons you might get a SEP, including losing employer health coverage or moving back to the U.S. after living in another country. 

Considering a Medicare Advantage or Medicare Supplement Plan?

Review options now.

Considering a Medicare Advantage or Medicare Supplement Plan?

Review options now.

When Will Your Benefits Start?

If you’re automatically enrolled, your benefits will start the first day of the month you turn 65. (Or if your birthday is the first day of the month, benefits start on the first day of the prior month.) You can apply for benefits if you’re at least 64 years and 9 months old, do not currently have any Medicare coverage, and aren’t receiving any Social security retirement, disability or survivors benefits.9 

You can also sign up for Medicare by phone by calling 800-772-1213 from 7 a.m. to 7 p.m. Monday through Friday. Or you can visit your local Social Security office. (Call first to make an appointment.)

If you must enroll for Medicare Part B, your coverage start date depends on when you sign up:

If you sign up for Part B in this month:Your coverage starts:
During first three months of initial enrollment periodThe first day of the month you turn 65, or if your birthday is the first day of the month, benefits start on the first day of the prior month
The month you turn 651 month after you sign up
1 month after you turn 652 months after you sign up
2 months after you turn 653 months after you sign up
3 months after you turn 653 months after you sign up
Source: U.S. Government Website for Medicare. “When will my coverage start?” medicare.gov (accessed May 2020).

Medicare benefits come with a Medicare card that you may need to present to healthcare providers.10 If you’re automatically enrolled, you’ll get your card in the mail three months before your 65th birthday. If you’re disabled and qualify for Medicare that way, you’ll get a card in the mail three months before your 25th month of disability benefits. If you’re eligible for Medicare because you have ALS, you can get your card the same month your disability benefits start.

You don’t have to enroll in Medicare annually, but each year you’ll have the chance to review your coverage and change plans if desired. You can make changes between October 15 and December 7.11 This is especially important if you know your medical needs may change, so put an annual reminder in your calendar in October to go over your options. 

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  1. U.S. Government Website for Medicare. “What Part B covers.” medicare.gov (accessed May 2020); U.S. Department of Health and Human Services. “What does Part B of Medicare (Medical Insurance) cover?” hhs.gov (accessed June 2020).

  2. U.S. Government Website for Medicare. “What’s not covered by Part A & Part B?” medicare.gov (accessed May 2020).

  3. U.S. Department of Health & Human Services. “Who is eligible for Medicare?” hhs.gov (accessed May 2020).

  4. U.S. Government Website for Medicare. “Part B costs.” medicare.gov (accessed May 2020).

  5. U.S. Government Website for Medicare. “Part B late enrollment penalty.” medicare.gov (accessed May 2020).

  6. U.S. Government Website for Medicare. “How do I get parts A & B?” medicare.gov (accessed May 2020).

  7. U.S. Government Website for Medicare. “Should I get Parts A & B?” medicare.gov (accessed May 2020).

  8. U.S. Government Website for Medicare. “Part A & Part B sign up periods.” medicare.gov (accessed May 2020).


  9. U.S. Government Website for Medicare. “When will my coverage start?” medicare.gov (accessed May 2020).

  10. U.S. Government Website for Medicare. “Your Medicare card.” medicare.gov (accessed May 2020).

  11. Centers for Medicare and Medicaid Services, “Medicare Open Enrollment,” cms.gov (accessed June 2020).