What Does Medicare Part B Cover? Outpatient Benefits Explained

What does Medicare Part B cover? It covers the medical care you get outside a hospital bed. That includes doctor visits, lab tests, preventive screenings, outpatient surgery, mental health care, and medical equipment you use at home. Part A pays for inpatient hospital stays.

Part B fills in nearly everything else. For most beneficiaries, it is the coverage they use most often. Families helping an aging parent should understand it too. Asking “what does medicare part b cover” before an appointment can prevent surprise bills, missed screenings, and costly enrollment mistakes. Part B is optional, but skipping it can bring lifelong penalties.

What Does Medicare Part B Cover? The Core Outpatient Benefits

Part B covers two broad types of services. The first is medically necessary care, meaning services needed to diagnose or treat a condition. The second is preventive care, which is meant to catch illness early or prevent it.

When people ask what does medicare part b cover, the everyday answer is long. Covered services include:

• Doctor and specialist visits, including in a hospital outpatient department
• Outpatient surgery at hospitals and ambulatory surgical centers
• Diagnostic tests such as X-rays, MRIs, CT scans, and EKGs
• Clinical lab work, such as blood tests and urinalysis
• Emergency room visits and ambulance transport when other transport would endanger your health
• Durable medical equipment (DME), such as walkers, wheelchairs, hospital beds, and oxygen
• Outpatient mental health care, including therapy and some partial hospitalization programs
• Physical, occupational, and speech therapy
• Limited home health care when Part A does not apply

Part B also pays for some drugs. In most cases, these are drugs a provider gives you in a clinic. Examples include infusions, certain injectables, some oral cancer drugs, and insulin used with a pump. However, most pills you pick up at a pharmacy fall under Part D, not Part B.

One detail catches many people off guard. If you stay in a hospital under “observation status,” you are an outpatient. As a result, Part B pays for that care, not Part A. Hospitals must give you a Medicare Outpatient Observation Notice (MOON) if you are under observation for more than 24 hours. Observation days also do not count toward the 3-day inpatient stay needed for skilled nursing facility coverage.

Preventive Services, Costs, and What Part B Does Not Cover

Preventive care is one of the most valuable parts of Part B. Many screenings cost you nothing if your provider accepts assignment. Accepting assignment means the provider agrees to take Medicare’s approved amount as full payment.

For non-preventive care, cost sharing applies. You pay a monthly premium and a yearly deductible. After that, you typically owe 20% coinsurance of the Medicare-approved amount. Original Medicare has no out-of-pocket cap. That is why many people add a Medigap policy or choose a Medicare Advantage plan. Higher-income beneficiaries also pay more through the Income-Related Monthly Adjustment Amount (IRMAA). The SSA bases IRMAA on your tax return from two years earlier.

Some providers do not accept assignment. These providers can charge up to 15% above the Medicare-approved amount, known as the “limiting charge.” For example, a specialist who does not accept assignment may bill you for the excess. Asking ahead of time helps you avoid that gap.

Knowing what does medicare part b cover also means knowing its limits. Part B generally does not pay for:

• Routine dental care, cleanings, and dentures
• Routine eye exams and eyeglasses, except after cataract surgery
• Hearing aids and fitting exams
• Long-term custodial care, such as help with bathing and dressing
• Most outpatient prescription drugs (those fall under Part D)
• Cosmetic surgery and routine foot care
• Acupuncture, except for chronic low back pain under specific conditions

Many Medicare Advantage plans from carriers like Humana, UnitedHealthcare, Aetna, and Blue Cross offer some of these extras. However, benefits, networks, and costs vary widely by plan and county.

How to Enroll and Get the Most From Part B

Timing matters with Part B. Your Initial Enrollment Period lasts 7 months. It starts 3 months before the month you turn 65 and ends 3 months after. If you already receive Social Security benefits, you are typically enrolled automatically. Otherwise, you sign up through the SSA.

Missing that window can be expensive. The late enrollment penalty adds 10% to your premium for each full 12-month period you could have had Part B but did not. In most cases, that penalty lasts as long as you have Part B. The General Enrollment Period runs January 1 through March 31 each year. Coverage then begins the first day of the month after you sign up.

There is an important exception. If you or your spouse have group health coverage through current employment, you may delay Part B. You then get an 8-month Special Enrollment Period after that job or coverage ends. Retiree coverage and COBRA do not count as current employment coverage.

Once enrolled, take these steps to use your benefits well:

1. Book your Welcome visit early. It is only available during your first 12 months of Part B.
2. Confirm assignment. Ask every provider whether they accept Medicare assignment before treatment.
3. Check coverage tools. Use the “Is my test, item, or service covered?” tool on Medicare.gov.
4. Review your Medicare Summary Notice. It arrives every 4 months and lists services billed to Medicare.
5. Weigh supplemental coverage. Your Medigap Open Enrollment Period lasts 6 months after you turn 65 and enroll in Part B. During that time, insurers like Mutual of Omaha, AARP/UnitedHealthcare, and Cigna cannot deny you for health reasons.
6. Explore cost help. Medicare Savings Programs, run by state Medicaid agencies, can pay Part B premiums for people with limited income.

Each of these steps gives you a clearer answer to what does medicare part b cover in your own situation. For free, unbiased guidance, contact your State Health Insurance Assistance Program. You can find a local counselor through SHIPhelp.org. SHIP counselors do not sell insurance, and their help costs nothing.

Frequently Asked Questions

What does Medicare Part B cover that Part A does not?

Part B covers outpatient services, while Part A covers inpatient care. For example, doctor visits, lab tests, outpatient surgery, and medical equipment fall under Part B. Observation stays in a hospital are also billed to Part B.

Is Medicare Part B mandatory?

No, Part B is optional. However, delaying it without employer group coverage can trigger a permanent 10% penalty for each late year. You may also face a gap in coverage while waiting for the General Enrollment Period.

Does Medicare Advantage cover everything Part B covers?

Yes. By law, Medicare Advantage plans must cover all Part A and Part B services. Typically, they use provider networks and set their own cost sharing. Many also add dental, vision, and hearing benefits. Still, you must keep paying your Part B premium.

Does Part B cover prescription drugs?

Only in limited cases. Part B covers drugs you usually cannot give yourself, such as infusions, certain vaccines, and some oral cancer drugs. As for what does medicare part b cover at the pharmacy counter, the answer is very little. Most retail prescriptions need a Part D plan.

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Official Sources & Resources

For verified information on Medicare regulations and consumer protection:

• Medicare.gov (Official Site): medicare.gov
• CMS (Centers for Medicare & Medicaid Services): cms.gov
• NAIC (National Association of Insurance Commissioners): naic.org
• KFF Medicare Research: kff.org/medicare
• Social Security Administration: ssa.gov

Content last reviewed October 2026. If you notice any outdated information, please contact us.

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