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What is Medicare Part B?

Medicare Part B, one of the two parts of Original Medicare, generally covers medical expenses and care, including medically necessary services and preventative services that may not be covered by Part A. On the other hand, Medicare Part A covers hospital-related health services and care, including inpatient hospital care, nursing care, and home health care.

Part A and Part B are designed to work together. While Part A provides coverage for services in hospital and hospice care, Part B handles the doctors’ visits and tests that help streamline patient treatments. Enrolling in Part B is optional, and you could choose to enroll only in Part B and not Part A. However, Part B is required if you want to buy Part A, but not if you are eligible for premium-free Part A.

What Does Medicare Part B Cover?

Medicare Part B primarily covers medically necessary services and preventative services, but may also cover medical equipment, prescription drugs, and other health services. Medically necessary services are those used to treat or diagnose medical conditions that meet accepted medical practice standards, while preventative services refer to healthcare services used to prevent or mitigate the impact of illness.

Medicare Advantage plans — also called Part C — are offered by private health insurance providers. These plans are Medicare-approved and combine aspects of Part A, Part B, and oftentimes Part D Medicare coverage. In practice, this means that Medicare Advantage plans may have a different mixture of coverage than typical Part A or Part B plans, but will still cover the basics of Original Medicare (Parts A and B). Advantage plans may also offer coverage for vision and dental services, which are not offered under Part B.

Part B includes coverage for the following:

  • Medically necessary services: Medically necessary services are used to diagnose or treat an injury, illness, or condition, or address its symptoms. Some examples of medically necessary services under Part B include X-rays, lab tests, and medication administered by medical professionals, such as IV drugs.
  • Preventative care: Preventative care services are used to reduce the risk of illness, detect potential issues, and keep patients healthy. Part B may cover preventative care services like disease screenings, vaccines, and counseling.
  • Medical equipment: Part B covers medically necessary equipment that doctors prescribe for patients’ use in their homes. Some examples of covered medical equipment include blood sugar meters, continuous positive airway pressure (CPAP) devices, patient lifts, traction equipment, and wheelchairs.
  • Prescription drugs: Medicare Part B covers some prescription drugs, but in a limited capacity. Examples include drugs used with medical equipment, such as those used with an infusion pump or nebulizer. It may also cover some antigen medications prepared by a doctor, injectable osteoporosis drugs, and blood clotting factors. It does not typically cover the types of medications that you would pick up from a pharmacy.
  • Mental health services: Some mental health services are covered under Medicare Part B, including inpatient, outpatient, and patient hospitalization services. In the case of outpatient services, Part B can help pay for one depression screening per year, family counseling, psychiatric evaluation, and an annual wellness visit.
  • Ambulance services: Medicare Part B covers ground ambulance transportation to a skilled nursing facility or hospital for medically necessary services. It may also cover limited non-emergency ambulance services if patients have a written order from their doctor that ambulance transport is necessary.

How Much Does Medicare Part B Cost?

Medicare Part B comes with 3 main costs: monthly premiums, coinsurance, and annual deductibles. There is also a penalty cost for late enrollment into Part B that should be considered when deciding if you want to enroll.

Medicare Part B premiums

Premiums for Medicare Part B are paid every month. The standard Part B premium in 2023 is $164.90. This will increase to $174.70 in 2024. However, the amount you actually pay is determined by the modified adjusted gross income reported on your 2021 tax return (2022 return for 2024). For example, if your individual tax return in 2021 was $97,000 or less, you would pay $164.90 every month in 2023 for your Part B premium. If your individual tax return in 2021 was between $97,001 and $123,000, you would pay $230.80 every month.

The Part B premium breakdown for 2023 is as follows:

Individual Income Range Based On 2021 Tax Return
Jointly Filed Income Range Based On 2021 Tax Return
Part B Premium Cost
Up to $97,000
Less than or equal to $194,000
$97,001 to $123,000
$194,001 to $246,000
$123,001 to $153,000
$246,001 to $306,000
$153,001 to $183,000
$306,001 to $366,000
$183,001 to $500,000
$366,001 to $750,000
$500,001 and higher
$750,001 and higher
Source:; accessed October 15, 2022

This will change to the following in 2024:

Individual Income Range Based On 2022 Tax Return
Jointly Filed Income Range Based On 2022 Tax Return
Part B Premium Cost
Up to $103,000
Less than or equal to $206,000
$103,001 to $129,000
$206,001 to $258,000
$129,001 to $161,000
$258,001 to $322,000
$161,001 to $193,000
$322,001 to $386,000
$193,001 to $500,000
$386,001 to $750,000
$500,001 and higher
$750,001 and higher
Source:; accessed October 18, 2023

If you receive benefits from the Railroad Retirement Board, the Office of Personnel Management (OPM), or through Social Security, your premium is automatically deducted from this amount.

Medicare Part B coinsurance

Once you’ve paid your Medicare Part B deductible, you typically pay 20% of the medically-approved amount for doctor services, outpatient therapy, and durable medical equipment as your coinsurance. While Medicare Part A may have copays, Medicare Part B has no copay amount for covered services.

Medicare Part B deductibles

The Medicare Part B deductible is $226 in 2023 ($240 in 2024). Once you fully pay your deductible, you pay 20% of the medically-approved amount for services. For example, let’s say the new coverage year has just started and you go to the doctor’s office. The bill comes to $200. Since you have not met and paid your deductible for the year yet, you are responsible for the entire cost. After $33 more in health spending, your deductible will be met and Medicare Part B will begin to cover up to 80% of medically-approved service costs.

Medicare Part B penalty cost for late enrollment

If you choose not to enroll in Medicare Part B when you first become eligible, you may have to pay ongoing penalty fees if you decide to enroll later. For each 12-month period that you could have had Part B, your monthly premium may increase by 10%. For example, if you have been eligible for Part B for the last 3 years but did not sign up until now, your monthly premiums could go up by 30% — 10% for each 12-month period you didn’t have coverage. 

It’s also worth noting that this penalty applies for as long as you have Part B, meaning the 30% premium increase is permanent.

Are You Eligible for Medicare Part B?

Eligibility for Part B includes being 65 or older, collecting disability benefits, and/or having end-stage renal disease (ESRD). If you are eligible for premium-free Medicare Part A, you are eligible for Part B.

If you need to pay a premium for Part A, you are eligible for Part B if you are 65 or older, are a U.S. resident, and are either a U.S. citizen or alien who has been lawfully admitted and has been residing in the United States for at least 5 continuous years before applying.

When Can You Enroll in Medicare Part B?

There are 4 enrollment periods for both Original Medicare and Medicare Part B:

  • Initial Enrollment Period: The Initial Enrollment Period is a 7-month window that starts three months before you turn 65, continues through your birthday month, and then for three months afterward. During this time, you can enroll in Medicare Part A or Part B, enroll in a Medicare Advantage Plan, or enroll in a Part D stand-alone prescription drug plan.
  • General Enrollment Period: This period occurs every year from January 1 to March 31 and allows you to sign up for Medicare Part A or B if you didn’t sign up during your initial enrollment period and you don’t qualify for a special enrollment period (SEP). Coverage for applications made during general enrollment starts July 1.
  • Annual Enrollment Period: This period lets you make changes to your existing Medicare plan from October 15 to December 7 each year. You can switch to or from Original Medicare or Medicare Advantage plans, join or drop a prescription drug plan, or change your current insurer. Any changes take effect on January 1.
  • Special Enrollment Period: This period lets you enroll in Part B outside of other standard enrollment periods without incurring a penalty. To be eligible, you must have employer-provided health coverage in the first month you are eligible for Part B. The Part B SEP is triggered when your employer-provided health coverage ends and lasts for 8 months.

Are There Reasons to Not Enroll in Medicare Part B?

You may have existing coverage through your employer that is more cost-effective than paying the Part B premiums, coinsurance, and deductibles, making it better to not enroll in Medicare Part B just yet. While you can generally apply for Medicare Part B once you’re 65, you may also choose to opt for private insurance rather than Part B even after retirement. However, remember that you may pay a permanent late enrollment penalty if you change your mind later.

How to Delay Part B Enrollment

Enrollment in Medicare Part B is optional. If you choose to delay your application, you could face a permanent penalty based on the number of consecutive 12-month periods where you were eligible for Part B but did not enroll.

However, if you currently have a job that provides coverage or are covered by similar insurance through your spouse’s job, you may be able to delay without facing enrollment penalties later due to the SEP that kicks in after employer-sponsored coverage ends.

How to Apply for Medicare Part B

If you’re looking to apply for Medicare Parts A and B, you can apply online at Social Security, call 1-800-772-1213, or contact your local Social Security office.

If you already have Part A and want to add Part B, you can call or make an in-person appointment with your local Social Security office. You could also fill out Form CMS-40B and mail or fax it to your local Social Security office to apply.

Bear in mind that because of the COVID-19 pandemic, your local Social Security office may not be allowing in-person enrollment at this time.

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