Medicare Part B: What It Is and What It Covers

Medicare, as many seniors and their caregivers know, is a federal program, funded by a combination of federal revenues, payroll taxes, and beneficiary premiums, that provides health insurance for older adults and some younger people with specific illnesses. If you are 65 or over, you are likely to have Medicare coverage, along with more than 68.5 million other Americans as of January 2025.

You may also be aware that Medicare is broken out into several parts: Part A, Part B, Part C, also called Medicare Advantage, and Part D. In this guide to Medicare Part B, we will look at questions such as What does Medicare Part B cover? And how much is Medicare Part B? 

Medicare Parts A and B are often referred to as Original Medicare. Part A, or Hospital Insurance, pays for most of your costs if you are an inpatient at a hospital or nursing facility, as the name suggests, as well as hospice costs. Medicare Part C, also called Medicare Advantage, bundles together Parts A and B, and is offered by private insurance companies rather than the government. Part D, meanwhile, covers many prescription drug costs and may be available as part of an Advantage plan, though it can also be purchased along with Original Medicare. 

So what is Medicare Part B? It's also called medical insurance, and it's the part of Medicare that covers costs you incur as an outpatient — that is, costs when you are not currently admitted to a hospital or skilled nursing facility. When you are living at home — whether that's your own home, an independent living residence, memory care facility, assisted living, or other living situation — Medicare Part B covers a wide range of medical expenses. 

More specifically, Medicare Part B pays for your outpatient care, clinical research, and any durable medical equipment you need to stay healthy or manage your health conditions. It may cover the costs of mental health or substance use disorder services, oxygen equipment, and ambulance services. Medicare Part B also, despite not being focused on hospital care, covers the cost of your doctors while you're in the hospital. 

In addition, Part B helps cover the costs of preventive services that aim to keep you healthy and avoid disease and illness, or at least aim to detect it as early as possible. Finally, Medicare Part B pays for medically necessary services to diagnose or treat your medical condition.

Medicare Part B covers a variety of medical services delivered on an outpatient basis:

• Emergency room care and observation services, which are considered outpatient services, whether or not you are later admitted to the hospital.
• Blood drawn at a hospital laboratory, as long as you’re not admitted at the time. 
• X-rays and other imaging tests performed at a hospital, provided you have them on an outpatient basis and not while you’re admitted.
• Limited drug coverage in certain circumstances, like oral ESRD medications for end-stage renal disease
• Injectables administered by a medical professional, drugs delivered via an infusion pump, blood-clotting factors, and some antigens.
• Outpatient therapies, including physical therapy, speech-language therapy, and occupational therapy received in a medical office setting, rehabilitation facility, or at home if you are housebound.

Preventive health services that can keep you from illness are important for older adults, and Medicare Part B will often cover them. This may include the following:

• Screenings of many types, designed to detect illnesses such as cardiovascular disease, cancers, and diabetes
• Immunizations, including annual flu shots
• Some chiropractic services
• Glaucoma tests
• Hearing and balance exams
• HIV testing
• Hepatitis B shots
• Mammograms
• Physical exams
• Smoking cessation programs

Durable medical equipment (DME) is any medical device designed to assist you or your loved one with disabilities or illness as prescribed by health care professionals. Durable medical equipment, as the name suggests, is intended for repeated use. In order for it to be paid for by Medicare Part B, it must be obtained from a Medicare-enrolled supplier. Some examples of DME include the following:

• Canes and walkers
• Commode chairs
• Blood sugar meters
• Crutches
• Hospital beds
• wheelchairs and scooters
• Nebulizers 
• CPAP machines
• Oxygen equipment and supplies

Although Medicare Part B covers many health-related costs, there are some services and supplies it does not include. This list includes most dental care, most eye exams, cosmetic surgery, hearing aids and exams, and massage therapy. 

One of the biggest exclusions from Medicare Part B, however, is long-term care, also called custodial care. This includes nursing home costs, as well as home-delivered meals, adult day health care, and home- and community-based services. This may also include the costs of having someone come to your home to help with your activities of daily living (ADLs). Whether you receive these services in your own home or in a facility such as a nursing home, they will not normally be covered by Medicare.

Unlike Medicare Part A, which has no premium for many people, you may pay several types of costs for your Part B coverage, including a monthly premium, deductibles, and coinsurance. These costs may be less than what you paid for your group health insurance or other coverage, but that depends on your previous plan and whether your employer paid into your premiums. Here's a rundown on what you can expect to pay for your Medicare Part B insurance:

• Premium: In 2025, the monthly premium for Part B is $185 if your annual income is $106,000 or less. If your income is over this amount, you could pay up to $628.90. Generally, the Part B premium increases every year. If you did not sign up for Medicare when you were first eligible, there may be a penalty added to this amount, which goes up the longer you wait.
• Deductible: If you have Original Medicare, you will pay a $257 deductible before Medicare starts to pay. Those with a Medicare Advantage plan may have a different 
• Coinsurance: Generally, your coinsurance, which is always a percentage of the cost, will be 20% after your deductible is met. In some cases, there is no coinsurance. For example, clinical lab services are fully covered, as is a yearly depression screening.

To be eligible for Medicare Part B, you must be a U.S. citizen or legal resident who has lived in the country for five consecutive years. You must either be age 65 or older or have a documented disability and have received disability benefits for 24 months. Those with specific conditions, such as ALS (Lou Gehrig’s Disease) or end-stage renal disease (ESRD), are exempt from this rule.

Generally, people who are eligible for Part A will also be eligible for Part B, and for most individuals, coverage will begin on the first day of the month of their 65th birthday. So, for example, if your birthday is December 15, you are eligible for Medicare to begin on December 1. 

To summarize, you need to meet the following eligibility requirements to qualify for Medicare Part B:

• U.S. citizen or lawful permanent resident
• At least 65 years old OR have a documented disability
• For most disabilities, you received 24 disability payments before qualifying

When you’re ready to enroll in Medicare, timing is everything. Although you can sign up for Medicare Part A at any time once you become eligible, you don’t have the same flexibility with Medicare Part B. You need to sign up during certain enrollment periods, or you may have to pay a higher premium the rest of the time you’re on Medicare.

For most people, the initial enrollment period for Medicare Part B lasts for seven months, starting three months before you turn 65 and ending three months after the month you turn 65. So if your birthday is June 10, your enrollment period begins March 1 and ends September 30. If you miss this period, you may end up paying a penalty that will continue as long as you have Medicare. 

If you don’t sign up during your initial enrollment period, you’ll have another opportunity during the general enrollment period. This happens every year from January 1 to March 31. Although you can sign up during this period, you may have to pay a late enrollment penalty. The penalty is a premium increase that remains in effect for the life of your Medicare coverage. When you sign up during this period, your coverage starts the month after you sign up.

There are a few special situations for which Medicare has created special enrollment periods. These include the following:

• Lost Medicaid Coverage: Your special enrollment period begins the day you are notified of Medicaid cancellation and ends six months after coverage ends.
• Natural Disaster or Emergency: Your special enrollment period begins the day the Federal, state, or local government declares the emergency or disaster and ends six months later.
• Missing Enrollment Due to Employer Error: If you missed your enrollment window because you received inaccurate information from your health plan or employer, your enrollment period begins when you notify the Social Security Administration (SSA) of the inaccurate information and ends six months later.
• Incarceration: If you were released from incarceration and missed the chance to sign up while you were incarcerated, your enrollment period lasts from the day you're released to 12 months later.
• Exceptional Conditions: Your enrollment period begins once you contact Social Security and ends six months later, if you’ve experienced exceptional conditions.
• Existing Health Insurance: If you have or had health insurance through your job, your spouse's job, or a family member's job if you are disabled, your enrollment period is from the first month after your initial enrollment period ends to eight months after the group coverage or your employment ends, whichever comes first.
• Volunteering or Serving in a Foreign Country: Your enrollment period lasts from the month after you're no longer a volunteer, the organization no longer has tax-exempt status, or you no longer have health insurance outside the U.S., and lasts for six months.
• TRICARE for Military Members: If you have TRICARE, your enrollment period begins when SSA notifies you and ends 12 months later.

If you start receiving retirement benefits from the Social Security Administration or Railroad Retirement Board at least four months before your 65th birthday, you’ll be automatically enrolled in Medicare Part B. If you’re receiving Social Security or Railroad Retirement Board disability benefits and only have Medicare Part A coverage, you’ll be enrolled automatically in Part B when you turn 65.

If you don’t qualify for automatic enrollment, you’ll have to apply for coverage. You can fill out this Medicare application on the SSA website. If you need help with the application, you can also visit a local Social Security office or call the Social Security Administration at 800-772-1213.

Medicare Parts A and B make up Original Medicare, but they differ significantly in what they cover and how they manage costs. As we noted above, Part A is used to cover many costs while you or your loved one is a patient in a hospital or skilled nursing facility. 

Part A also pays for hospice care and some home health services. Part B, meanwhile, generally pays for outpatient supplies and services, as well as emergency services and doctors' costs when you're in a hospital or other Medicare-approved facility. 

Medicare Part A has no premium for most individuals, but Part B does. In 2025, this premium is $185 or more, depending on your income. Part A's deductible is $1,676 for each inpatient benefit period, while Part B's deductible is a yearly $257. Part A has copays for inpatient and skilled nursing facility stays, while both Parts A and B have coinsurance costs, which are generally 20% for select supplies and services. 

Medicare Parts A and B make up Original Medicare. While Part A covers inpatient hospital and skilled nursing facility costs during rehabilitation, Part B provides coverage for outpatient supplies and services, from doctors' visits to durable medical equipment. The two parts offer an extensive blanket of coverage for adults aged 65 and over, as well as some younger people who qualify due to certain disabilities or medical conditions.Medicare Part B does have some costs, including a monthly premium, as well as an annual deductible and coinsurance costs, which are generally 20% of the covered cost.

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