Medicare Part B is medical insurance. It covers doctor visits, outpatient care, preventive services, durable medical equipment, mental health care, and many lab and diagnostic tests.
Major categories Part B covers:
- Doctor visits: Primary care, specialists, second opinions. After the $283 annual deductible (2026), you pay 20% of the Medicare-approved amount; Medicare pays 80%.
- Outpatient hospital services: Same-day surgery, emergency department visits, observation services, X-rays.
- Preventive services: Annual wellness visit, flu/pneumonia/COVID/shingles vaccines, mammograms, colonoscopies, prostate screenings, cardiovascular screenings, diabetes screenings — most preventive services are $0.
- Lab tests: Blood work, urinalysis, biopsies, screening tests when medically necessary. Most labs are $0 if Medicare-approved.
- Mental health: Outpatient therapy, psychiatric visits, family counseling related to your treatment, partial hospitalization programs.
- Durable medical equipment (DME): Wheelchairs, walkers, oxygen, hospital beds, CPAP machines, blood-sugar meters and test strips, prosthetics, orthotics. Must be medically necessary and from a Medicare-enrolled supplier.
- Ambulance services: Emergency ground ambulance and air ambulance when medically necessary and ground would put your health at risk.
- Some home health services: Continuing skilled care that started under Part A coverage.
- Outpatient physical therapy, occupational therapy, speech-language pathology: Subject to medical necessity.
- Diabetes self-management training: Up to 10 hours initially, plus 2 hours per year for follow-up.
- Limited Part B drugs: Drugs that are typically infused or injected in a doctor's office (not oral medications you'd pick up at a pharmacy — those are Part D). Common Part B drugs: chemotherapy infusions, intravenous antibiotics in a clinical setting, immunosuppressants for transplant patients.
What Part B does NOT cover:
- Most prescription drugs (that's Part D)
- Routine dental care, dentures, dental implants
- Routine eye exams for glasses
- Hearing aids and exams for fitting hearing aids
- Most cosmetic surgery
- Routine foot care
- Long-term custodial care
- Acupuncture EXCEPT 12 visits in 90 days for chronic low back pain (limited expansion)
- Care outside the U.S. (with very narrow exceptions)
What you pay for Part B:
- Standard premium 2026: $202.90/month (deducted from Social Security if you collect it)
- Higher-income beneficiaries pay IRMAA surcharges on top (see our IRMAA answer)
- Annual deductible: $283 (2026), then 20% coinsurance on most services with NO out-of-pocket maximum
- This lack of OOP cap is why most beneficiaries either join Medicare Advantage (which has a cap) or buy a Medigap policy to cover the 20%
Late enrollment penalty: If you don't sign up for Part B during your IEP and don't have other creditable coverage, you pay a 10% premium surcharge for every 12-month period you delayed — for the rest of your life. The penalty is often the deciding factor for people working past 65.
What to do next: Call (866) 534-1886. We confirm whether you should enroll in Part B at 65, time it to avoid penalties, and pair it with the right Medigap or Medicare Advantage plan to cap your out-of-pocket. Free.