📋 Facts sourced from Medicare & You 2026, the official U.S. government Medicare handbook.

The Basic Rule: What Part B Is For

According to Medicare & You 2026, Part B (Medical Insurance) covers medically necessary doctor's services, outpatient care, some home health services, durable medical equipment, mental health services, limited outpatient prescription drugs, and other medical services. Part B also covers many preventive services.

The key phrase is "medically necessary" — meaning your doctor or other qualified provider has determined a service is needed to diagnose or treat your condition. Part B is not designed to cover things Medicare considers routine or elective.

How Part B Cost-Sharing Works (2026)

Annual deductible$283 per year
Your share after deductible20% of Medicare-approved amount
Medicare's share80% of Medicare-approved amount
Most preventive services$0 if provider accepts assignment
Yearly out-of-pocket capNone in Original Medicare
No out-of-pocket cap — this is important

Original Medicare Part B has no yearly limit on what you could pay out of pocket. If you have a serious illness requiring many Part B services, the 20% coinsurance can add up to a very large number with no ceiling. This is one of the primary reasons many people add a Medigap plan — to cap their exposure. Medicare Advantage Plans (Part C) are required to have an out-of-pocket maximum.

Major Categories of Part B Coverage

Part B covers a wide range of services. Here are the main categories with plain-English explanations of what each includes:

🩺 Doctor Services

Services from physicians, nurse practitioners, physician assistants, and other qualified health care providers — whether you see them in an office, a clinic, or as an outpatient at a hospital. After your $283 deductible, you pay 20%.

🏥 Outpatient Hospital Services

Services you receive in a hospital setting without being admitted as an inpatient — including emergency room visits, outpatient surgery, observation services, and outpatient clinic visits.

🧪 Lab Tests & Diagnostics

Blood tests, urinalysis, certain screening tests, and other diagnostic lab work ordered by your provider. Many lab tests are covered at $0 if they're ordered as preventive services.

📷 Imaging & X-Rays

Medically necessary X-rays, MRIs, CT scans, ultrasounds, and other imaging. After your deductible, you pay 20%. Prior authorization may be required for some imaging in Medicare Advantage plans.

♿ Durable Medical Equipment

Wheelchairs, walkers, hospital beds, oxygen equipment, CPAP devices, blood sugar monitors, and other durable equipment prescribed by your doctor for home use. You pay 20% after deductible.

🧠 Mental Health Services

Outpatient mental health care — including visits with psychiatrists, psychologists, licensed clinical social workers, and other mental health providers. Inpatient psychiatric facility care is covered under Part A.

🏠 Home Health Services

Part-time skilled nursing care, physical therapy, occupational therapy, and speech therapy in your home — if you're homebound and your doctor certifies you need it. Covered at $0 for most services when through a Medicare-certified agency.

🚑 Ambulance Services

Ground and air ambulance transportation when medically necessary — meaning travel by any other means could endanger your health. Medicare only covers transport to the nearest appropriate facility. You pay 20% after deductible.

Preventive Services: The $0 Benefit Most People Underuse

According to Medicare & You 2026, you pay nothing for most covered preventive services if you use a provider who accepts assignment. This is one of the most valuable — and most overlooked — parts of Part B.

Part B preventive services covered at $0 (when provider accepts assignment) include:

Important: Preventive vs. diagnostic — the billing difference

If you go in for a scheduled preventive colonoscopy and a polyp is found and removed during the same visit, Medicare may reclassify part of that visit as diagnostic — which means cost-sharing can apply. This surprises many people who expected a $0 bill. Always ask your provider how a service will be billed before your appointment, especially for screenings that might involve treatment.

What Part B Does NOT Cover

According to Medicare & You 2026, Part B does not cover: routine eye exams (for glasses or contact lenses), hearing aids or exams for fitting hearing aids, most dental care (routine cleanings, fillings, dentures), cosmetic surgery, or long-term personal care (like help with bathing or dressing at home when no skilled care is needed).

These gaps are one reason many people add a Medicare Advantage Plan (which may cover dental, vision, and hearing) or a Medigap plan (which covers cost-sharing but not new benefits). Understanding these gaps before you make a coverage decision matters a great deal.

Acupuncture — A More Limited Benefit

According to Medicare & You 2026, Medicare covers acupuncture only for chronic low back pain that has lasted at least 12 weeks, has no known cause, and is not related to surgery or pregnancy. Coverage is limited to up to 12 visits in 90 days, with an additional 8 sessions possible if you show improvement — up to 20 treatments in a 12-month period. The Part B deductible and 20% coinsurance apply.

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Betsy's Take

"One thing I always tell clients: use your free preventive services. People pay their Part B premium every month and then skip their wellness visit or their cancer screenings. Those are covered at $0. Your annual wellness visit is also a great time to do advance care planning — documenting your health wishes — which Medicare covers as part of that visit. These are real benefits that people leave on the table every year."

Talk to Betsy — Free Consultation

How the 20% Coinsurance Adds Up

The 20% you owe after your deductible sounds manageable — until you do the math on a serious condition. If Medicare approves $50,000 in Part B services (not unusual after a cancer diagnosis or major surgery), your 20% share is $10,000 with no cap above it. Medicare Advantage plans cap your out-of-pocket exposure. Medigap plans may cover all or part of that 20%. This is exactly the kind of planning Betsy helps clients think through before they need it.