Medicare Part B covers outpatient medical services, doctor visits, preventive care, durable medical equipment, and certain prescription drugs. It’s the “medical insurance” half of Original Medicare, designed to pay for care you receive outside of a hospital stay. In 2025, the standard monthly premium is $185.00, with an annual deductible of $257 before coverage kicks in.
Two Categories of Covered Services
Part B divides its coverage into two broad buckets. The first is medically necessary services: anything that meets accepted standards of medical practice to diagnose or treat a condition you have. The second is preventive services: care designed to prevent illness or catch it early, when treatment works best. This distinction matters because most preventive services are completely free to you, while medically necessary services typically require you to pay 20% of the cost after your deductible.
Doctor Visits and Outpatient Care
Part B pays for visits to your doctor’s office, outpatient surgeries, diagnostic tests, and lab work. Once you’ve met your annual deductible, you generally pay 20% of the Medicare-approved amount for each service, as long as your provider accepts assignment (meaning they agree to Medicare’s pricing). Clinical laboratory services, like blood tests ordered by your doctor, cost you nothing out of pocket. Home health care services that qualify are also covered at no charge.
Preventive Screenings and Vaccines
You pay nothing for most preventive services when you see a provider who accepts assignment. The list is extensive and covers screenings across nearly every major health concern for older adults:
- Cancer screenings: mammograms, colonoscopies, lung cancer screenings with low-dose CT, prostate cancer screenings, and cervical/vaginal cancer screenings
- Heart and metabolic screenings: cardiovascular disease screenings, diabetes screenings, and cardiovascular behavioral therapy
- Infectious disease screenings: HIV, hepatitis B, hepatitis C, and sexually transmitted infections
- Mental health: one depression screening per year at a primary care office
- Other screenings: bone mass measurements, glaucoma tests, abdominal aortic aneurysm screenings, and alcohol misuse counseling
Part B also covers four key vaccines at no cost: flu shots, pneumococcal shots, hepatitis B shots (for people at intermediate to high risk), and COVID-19 vaccines.
Two important wellness visits round out the preventive benefits. The one-time “Welcome to Medicare” visit is available within your first 12 months of enrollment and includes a review of your health risks, including depression. After that, you’re eligible for a yearly wellness visit to update your prevention plan and discuss any changes in your health.
Durable Medical Equipment
Part B covers medically necessary equipment prescribed by your doctor for use in your home. To qualify, the equipment must be durable enough for repeated use, serve a medical purpose, be primarily useful to someone who is sick or injured, and be expected to last at least three years.
Covered items include wheelchairs and scooters, walkers, canes, crutches, hospital beds, oxygen equipment, CPAP machines for sleep apnea, glucose monitors with test strips and lancets, infusion pumps, and commode chairs. You pay 20% of the Medicare-approved amount after your deductible.
Mental Health Services
Part B provides broad outpatient mental health coverage that goes well beyond the annual depression screening. It pays for individual and group psychotherapy, psychiatric evaluations, medication management, family counseling (when the goal is to support your treatment), and diagnostic testing to evaluate whether your current treatment is working. Partial hospitalization and intensive outpatient programs are also covered.
More recent additions include safety planning interventions for people at risk of suicide or overdose, follow-up phone calls after an emergency department visit for a behavioral health crisis, and FDA-cleared digital mental health treatment devices, including devices that treat ADHD. Mental health services received as part of substance use disorder treatment are covered as well.
Ambulance Services
Part B covers ground ambulance transportation when traveling by any other vehicle would endanger your health and you need to reach a hospital, critical access hospital, rural emergency hospital, or skilled nursing facility. Coverage applies only to the nearest appropriate facility that can provide the care you need.
Air ambulance transport by helicopter or airplane is covered when you need immediate, rapid transport that ground vehicles can’t provide. In some cases, Medicare also pays for non-emergency ambulance rides if your doctor provides a written order stating the transportation is medically necessary. If you receive scheduled non-emergency ambulance transport frequently (three or more round trips in 10 days, or at least once a week for three weeks), your ambulance company may need to get prior authorization. After your deductible, you pay 20%.
Prescription Drugs Under Part B
Most prescription drugs fall under Part D, but Part B covers a specific subset. The general rule: if a drug is administered by a healthcare provider rather than something you take on your own at home, Part B typically pays for it. This includes chemotherapy infusions, injectable drugs given in a doctor’s office, and medications delivered through covered equipment like nebulizers or infusion pumps at home.
Part B also covers certain oral anti-cancer drugs, oral anti-nausea drugs used alongside chemotherapy, immunosuppressive drugs for people who had a Medicare-covered organ transplant, clotting factors for hemophilia, and parenteral nutrition for people with permanent digestive tract dysfunction. The flu, pneumococcal, and hepatitis B vaccines fall under Part B rather than Part D.
What Part B Does Not Cover
Several common health services fall outside Part B’s scope entirely. The most notable exclusions are routine dental care (cleanings, fillings, extractions, dentures), eye exams for prescription glasses, hearing aids and the fitting exams for them, long-term custodial care, cosmetic surgery, massage therapy, and routine physical exams (the yearly wellness visit is not the same as a traditional physical). If your doctor has opted out of Medicare, Part B won’t cover services from that provider except in emergencies.
What You Pay
The standard Part B premium in 2025 is $185.00 per month, deducted automatically from your Social Security check in most cases. Higher-income beneficiaries pay more through income-related monthly adjustment amounts. The annual deductible is $257, which you pay once per calendar year before Part B starts sharing costs. After that, the standard split is 80/20: Medicare pays 80% of the approved amount, and you pay the remaining 20% for most services.
Preventive services and clinical lab tests are the major exceptions, costing you nothing. Some people purchase supplemental Medigap insurance specifically to cover the 20% coinsurance, which can add up quickly for expensive treatments like chemotherapy or major outpatient procedures.
Late Enrollment Penalties
If you don’t sign up for Part B when you’re first eligible and you don’t have qualifying coverage through an employer, you’ll face a permanent penalty. The surcharge is an extra 10% added to your monthly premium for every full 12-month period you could have had Part B but didn’t. This penalty applies for as long as you have Part B, which for most people means the rest of their lives.