Medicare Part B Explained

What is Medicare Part B?

Medicare Part B is sometimes called “medical insurance.” It covers doctor’s office visits and labs, x-rays, outpatient, and preventive services not covered by Part A. Most people pay a monthly premium for Part B. Medicare Part B is optional, but if you do not sign up when you are first eligible, you may have to pay a late enrollment penalty.

What does Medicare Part B cover?

Medicare Part B coverage is split into two categories: medically necessary services and preventive services. The Centers for Medicare & Medicaid Services (CMS) describes medically necessary services as “services or supplies needed to diagnose or treat your medical condition and that meet accepted standards of medical practice.”

Medically necessary services

• Doctor and other health care provider services like outpatient services, office visits, and consultations. This includes getting stiches or a cast, or any visit where you are not admitted as an inpatient.
• Outpatient surgery, meaning minor surgeries and services received in a hospital outpatient department or clinic where you are not admitted for an inpatient stay. 
• Lab and x-ray services that include a wide range of clinical lab tests to diagnose and treat medical conditions under Medicare Part B. Diagnostic imaging services like x-rays, CT scans, and PET scans are covered when medically necessary.
• Ambulance services, meaning transportation to the nearest medical facility when other transportation could endanger your health.
• Outpatient mental health services including counseling, psychotherapy, and some prescriptions for mental health conditions.
• Some prescription drugs, like chemotherapy and injectable medications, that you would receive in a doctor’s office or outpatient facility.
• Durable medical equipment like prosthetics, wheelchairs, and hospital beds prescribed for use in your home.

Preventive services

• Screenings for conditions such as cancer, diabetes, cardiovascular disease, and more.
  
• Vaccines like influenza, pneumococcal infections, hepatitis B (for individuals at high risk), and COVID-19.
• Nutrition therapy services provided by a registered dietitian or other qualified nutrition professional. This may include counseling for chronic conditions like obesity, hypertension, or cardiovascular disease if prescribed by a healthcare provider. 
• Counseling services for smoking cessation, obesity, alcohol dependency, depression, and other behavioral health issues.
• Outpatient mental health services like individual or group therapy sessions with a qualified mental health professional, diagnostic assessments to diagnose mental health conditions, depression screenings, substance abuse treatment, family counseling, and more.
• Yearly wellness visits: one visit every 12 months. The visit will include a medical history review, risk factors, and a personalized prevention plan.

Not sure if your service or product is covered? Find out what Medicare covers.

What does Medicare Part B not cover?

Part B does not cover any of the following items or services:

• Routine hearing, dental, and vision exams
• Hearing aids or glasses (except for glasses after cataract surgery)
• Emergency assistance while traveling outside the U.S.
• Fitness club membership
• Long-term care (such as a nursing home)
• Most prescription drugs

How much does Medicare Part B cost?

Part B requires you to pay a monthly premium, calculated based on your adjusted gross income, along with a yearly deductible before coverage begins. You are also responsible for paying part of the costs that Part B does not cover. In 2025, the standard monthly premium is $185, and the standard yearly deductible for 2025 is $257.

Your costs include:

• Your Medicare Part B monthly premium, if applicable.
• Yearly deductible (paid before Medicare begins paying).
• Coinsurance (percentage of the cost that Medicare does not pay).

Learn more about 2025 Medicare Parts A & B premiums and deductibles.

Can I get Medicare Part B for free?

Medicare Part B is free for low-income individuals enrolled in a Medicare savings program. This helps pay for premiums, deductibles, coinsurance, and copays. To qualify, individuals must meet specific income requirements. These requirements are updated yearly based on federal poverty level guidelines.  

Visit Medicare Savings Programs to see if you qualify. 

Medicare Part B eligibility requirements

You can enroll in Medicare Part B if:
• You are age 65 or older.
• You are under age 65 with certain disabilities.
• You have permanent kidney failure requiring dialysis.

How to sign up for Medicare Part B

If you already get benefits from Social Security, you'll get Medicare Parts A and  B automatically when you're first eligible and don't need to sign up. Medicare will send you a "Welcome to Medicare" packet three months before you turn 65. You can also contact the Social Security Administration to sign up for Original Medicare. Go to SSA.gov or call toll-free 1-800-772-1213 Monday through Friday from 8 a.m. to 7 p.m. TTY users should call 1-800-325-0778.