What Does Medicare Part B Cover? A Complete Guide for Caregivers

Medicare Part B is the half of Original Medicare that pays for doctor visits, outpatient procedures, preventive screenings, and medical equipment. If Part A is "hospital insurance," Part B is "everything outside the hospital" — though the line between the two is not nearly as clean as that sounds.

If you're helping a parent navigate Medicare, Part B is where most of the day-to-day healthcare spending happens. It's also where most of the confusion lives, because Part B covers some things you'd never expect (ambulance rides, second surgical opinions) and excludes things you'd assume any health plan would include (dental cleanings, hearing aids, routine eye exams).

This article breaks down exactly what Part B covers, what it costs, and the specific gaps that catch families off guard.

What Part B covers

Doctor and outpatient services

Part B covers medically necessary services provided by doctors, nurse practitioners, and other healthcare providers. This includes:

• Office visits with your parent's primary care doctor or any specialist
• Outpatient surgery at a hospital or ambulatory surgical center
• Second opinions before surgery (Medicare actually encourages this)
• Diagnostic tests — X-rays, MRIs, CT scans, blood work, and lab tests ordered by a doctor
• Outpatient mental health services — therapy sessions, psychiatric evaluations, and partial hospitalization for mental health treatment

"Medically necessary" is the key phrase. Medicare defines this as services or supplies needed to diagnose or treat a medical condition that meet accepted standards of medical practice. If a doctor orders it for a legitimate medical reason, Part B generally covers it.

Preventive services

Part B covers a wide range of preventive screenings and wellness visits at no cost to your parent — meaning no deductible and no coinsurance for these specific services:

• Annual wellness visit (the "Welcome to Medicare" visit in the first year, then yearly wellness visits after that)
• Flu shots, pneumonia vaccines, hepatitis B vaccines, and COVID-19 vaccines
• Cancer screenings — mammograms, colonoscopies, prostate cancer screening (PSA test), cervical and vaginal cancer screening, lung cancer screening for qualifying smokers
• Cardiovascular screening — cholesterol, lipid, and triglyceride levels every 5 years
• Diabetes screening for those at risk
• Depression screening annually
• Bone density measurement for those at risk of osteoporosis
• Obesity counseling and nutritional therapy for diabetes or kidney disease
• Abdominal aortic aneurysm screening (one-time, for qualifying individuals)

The critical detail: these screenings are free only when they're coded as preventive. If a colonoscopy finds a polyp and the doctor removes it during the procedure, it can be reclassified from "screening" to "diagnostic" — and suddenly your parent owes coinsurance. This billing reclassification catches families by surprise every year.

Durable medical equipment (DME)

Part B covers medically necessary equipment prescribed by a doctor for use in the home:

• Wheelchairs and power scooters
• Hospital beds
• Walkers, canes, and crutches
• Oxygen equipment and supplies
• CPAP machines for sleep apnea
• Blood sugar monitors and testing supplies for diabetics
• Nebulizers for breathing treatments

Medicare pays 80% of the approved amount for DME after the annual deductible is met. Your parent pays the remaining 20%. The equipment must be ordered by a Medicare-enrolled doctor and supplied by a Medicare-approved supplier — if either condition isn't met, Medicare won't pay.

Ambulance services

Part B covers ambulance transportation when your parent's medical condition requires it and other forms of transportation would endanger their health. This includes both emergency ambulance trips and, in some cases, non-emergency ambulance transport (for example, to a dialysis center when the patient cannot safely travel by car).

Other services many families don't realize are covered

• Clinical research studies — if your parent is in a qualifying clinical trial, Part B covers routine costs
• Telehealth services — expanded significantly in recent years, including virtual doctor visits
• Outpatient physical therapy, occupational therapy, and speech therapy
• Home health services — part-time skilled nursing care, physical therapy, and medical social services when a doctor certifies the patient is homebound
• Outpatient prescription drugs administered in a doctor's office or hospital outpatient setting (chemotherapy infusions, injectable osteoporosis drugs, etc.) — these fall under Part B, not Part D

That last point matters enormously for families dealing with cancer or chronic conditions. Drugs your parent takes at home (pills, patches) are covered under Part D. But drugs administered by a healthcare professional in a clinical setting — including chemotherapy — are covered under Part B. The coverage rules, costs, and formularies are completely different between the two.

What Part B costs in 2026

The premium

The standard Part B premium for 2026 is $185 per month. Most people pay this amount, which is typically deducted directly from their Social Security check.

However, if your parent's modified adjusted gross income (MAGI) is above $106,000 (individual) or $212,000 (married filing jointly), they'll pay a higher premium through the Income-Related Monthly Adjustment Amount (IRMAA). The surcharges are significant — the highest income bracket pays over $500/month for Part B alone.

IRMAA is based on the tax return from two years prior. So your parent's 2026 premium is based on their 2024 tax return. If they had a one-time income spike (sold a house, took a large IRA distribution), they can file an appeal with Social Security using Form SSA-44.

The deductible

The annual Part B deductible for 2026 is $257. Your parent pays 100% of covered services until they've spent $257 in a calendar year. After that, Medicare pays its share.

Coinsurance

After the deductible is met, your parent typically pays 20% of the Medicare-approved amount for most Part B services. Medicare pays the other 80%.

There is no annual out-of-pocket maximum under Original Medicare. This is the single biggest financial risk of Part B — if your parent has a major medical event (cancer treatment, extensive outpatient surgery, long-term therapy), that 20% coinsurance has no cap. It can add up to tens of thousands of dollars.

This is exactly why Medicare Supplement (Medigap) plans exist. A Medigap plan covers the 20% coinsurance gap. Without one, your parent is exposed to unlimited cost-sharing on the Part B side.

What Part B does NOT cover

These are the gaps that most often surprise families:

• Routine dental care — cleanings, fillings, dentures, extractions (with very limited exceptions for certain dental procedures tied to a covered medical condition)
• Routine eye exams and eyeglasses — Part B covers eye exams for glaucoma risk and cataract surgery, but not standard vision exams or prescription glasses
• Hearing aids and routine hearing exams — Part B does not cover hearing aids (which can cost $1,000-$6,000 per pair)
• Most prescription drugs taken at home — these are covered under Part D, not Part B
• Long-term care — nursing home stays, assisted living, and custodial care are not covered by any part of Medicare
• Care outside the United States — with very limited exceptions for emergency situations near the border
• Cosmetic surgery

Dental, vision, and hearing are the three gaps that frustrate families the most. These are basic healthcare needs that nearly every senior requires, yet Original Medicare excludes them. Some Medicare Advantage plans bundle these benefits, which is one reason Advantage plans are marketed so heavily — but the trade-offs in network restrictions and prior authorization requirements are significant.

How Part B works with other coverage

Part B + Medigap

A Medigap (Medicare Supplement) plan pairs with Parts A and B to cover most or all of the out-of-pocket costs. The most popular Medigap plans — Plan G and Plan N — cover the 20% Part B coinsurance, which eliminates the risk of unlimited cost-sharing. With Plan G, your parent's only out-of-pocket cost for Part B services is the $257 annual deductible.

Part B + Medicare Advantage

If your parent enrolls in a Medicare Advantage plan (Part C), the Advantage plan replaces the way Part B benefits are delivered. They still have Part B — they still pay the Part B premium — but the Advantage plan sets its own copays, coinsurance, and network rules. Advantage plans must cover everything Original Medicare covers, but they can charge differently and restrict which providers your parent can see.

Part B + employer coverage

If your parent is still working at age 65 (or covered by a working spouse's employer plan), the employer plan typically pays first and Medicare Part B pays second. This coordination of benefits can be confusing, and it matters for deciding when to enroll in Part B. If the employer has 20 or more employees, your parent can usually delay Part B without penalty while the employer coverage is active.

The Part B enrollment timing trap

Part B enrollment is not automatic for everyone. If your parent is already receiving Social Security benefits when they turn 65, they'll be automatically enrolled. But if they're still working and haven't filed for Social Security, they need to actively sign up during their Initial Enrollment Period — the 7-month window around their 65th birthday.

Missing this window triggers the late enrollment penalty — a permanent 10% premium surcharge for every year they could have had Part B but didn't. And they can only enroll during the General Enrollment Period (January 1 through March 31 each year), with coverage not starting until July 1.

Protecting your parent from Part B costs

The 20% coinsurance with no cap is the financial vulnerability that every family managing a parent's Medicare needs to address. A single hospital outpatient procedure can generate thousands in Part B charges, and 20% of that comes directly out of pocket.

There are two ways to address this: a Medigap supplement plan (which covers the gap but costs a monthly premium) or a Medicare Advantage plan (which has an annual out-of-pocket maximum but restricts provider choice). Both approaches have trade-offs, and the right choice depends on your parent's health, location, and financial situation.

If you're sorting through these decisions for your parent, our Medicare Enrollment Guide includes a Part B coverage worksheet and a side-by-side comparison tool for evaluating supplement and Advantage options — designed specifically for adult children managing a parent's Medicare choices.