Here's the short answer. Medicare Part B covers your outpatient medical care, like doctor visits, preventive screenings, equipment, and some outpatient mental health and rehab services. You pay a monthly premium plus a share of costs for each service. Enrolling on time and choosing providers who accept Medicare can help keep your costs predictable.
What is Medicare Part B?
Medicare Part B is the medical insurance part of Original Medicare. It pays for care you get outside a hospital stay. That means doctor visits, preventive care, lab tests, and medical equipment. Part A covers hospital stays. Part B covers most everything else a doctor orders.
Medicare Part B in four quick facts
- What it covers. Doctor and clinic visits, outpatient care, screenings and shots, lab work and imaging, and equipment like walkers.
- What you pay. A monthly premium. Then you pay your deductible. After that, you usually pay 20% of the approved cost of each service.
- What it leaves out. Most oral prescription drugs. Those are covered under Part D.
- How to get it. Part B is optional. Some people sign up automatically and others must sign up. See Enrollment & Deadlines.
Ask each provider if they accept Medicare's approved amount. That is called accepting assignment, and it keeps your bills predictable. If you want help with the 20% share, see Medigap.
What Part B Covers
Medicare Part B pays for medical services and equipment you receive outside a hospital. It works alongside Medicare Part A (hospital insurance). Part A covers hospital stays. Part B covers doctor office visits, clinic visits, and hospital outpatient services.
| Service Category | What's Included |
|---|---|
| Physician Services | Office visits, consultations, diagnostic exams, and specialist care |
| Hospital Outpatient Care | Emergency department visits and ambulance rides, outpatient surgery, imaging, and lab work at a hospital |
| Preventive Care | Yearly Wellness visit (not a routine physical), screenings (cancer, cardiovascular, bone density), vaccinations like flu and COVID-19 shots, and counseling |
| Laboratory and Imaging | Blood tests, X-rays, ultrasounds, CT scans, and other diagnostic studies |
| Durable Medical Equipment | Wheelchairs, walkers, oxygen, hospital beds, diabetic testing supplies and glucose monitors, and other devices approved by Medicare |
| Mental Health Services | Psychiatrist or psychologist office visits, including therapy and mental health care and crisis intervention |
| Rehabilitation Services | Physical therapy, occupational therapy, and speech therapy (when medically necessary) |
| Chiropractic and Acupuncture | Spinal manipulation by a chiropractor for subluxation, and acupuncture only for chronic low back pain (up to 12 treatments in 90 days); X-rays and massage from a chiropractor are not covered |
| Limited Medications | Certain drugs administered by a physician or in an outpatient setting (e.g., chemotherapy, biologics). Oral prescription drugs are covered under Part D |
| Telehealth | Video and some phone visits with your provider, from anywhere in the U.S. including your home, through December 31, 2027 |
How Much You Pay
Monthly Premium
Most people pay a monthly premium for Medicare Part B. The Centers for Medicare & Medicaid Services (CMS) sets the standard premium each year. If your income is modest, you pay the standard premium. If your income is higher, you may pay more under a rule called Income-Related Monthly Adjustment Amount (IRMAA).
IRMAA applies if your income is above certain thresholds. The thresholds vary based on your filing status and change each year. If IRMAA applies to you, you pay the standard premium plus an extra amount. The extra amount is based on how much your income exceeds the threshold. For current amounts and brackets, visit Medicare.gov or call Social Security.
Annual Deductible and Cost-Sharing
After you pay your monthly premium, you have out-of-pocket costs when you get care. Medicare Part B has an annual deductible (an amount you pay before insurance kicks in). Once you meet the deductible, Medicare covers 80% of approved charges. You pay the remaining 20% coinsurance (your share).
Your costs depend on your provider type. A participating provider accepts Medicare and agrees to accept Medicare's approved charge as full payment. A non-participating provider may charge more. Learn more about that below. For current deductible amounts and cost-sharing details, see the Understanding Your Costs page or visit Medicare.gov.
Participating Providers and Assignment
When you receive care, the type of provider matters for your out-of-pocket costs. Medicare providers fall into two categories:
- Participating Providers: These doctors and suppliers have signed an agreement with Medicare. They accept Medicare's approved charge and bill Medicare and you directly. You pay only your 20% coinsurance (the amount you share) after your deductible. This is predictable and straightforward.
- Non-Participating Providers: These providers have not signed a participating agreement with Medicare. They can charge you extra. When they don't accept assignment (treat the claim like a participating provider), they can charge you up to 15% more than Medicare's approved amount. You pay that extra charge.
To see if a doctor or supplier participates in Medicare, use the Medicare.gov provider search. Full guide: Does my doctor accept Medicare? explains assignment, the 15% limiting charge, and doctors who have opted out of Medicare entirely.
Excess Charges and Medigap
Extra charges can add up fast. If you see a non-participating provider who doesn't accept assignment, your bills may be much higher than your expected 20% coinsurance. Many people buy Medigap (Medicare Supplement Insurance) to help pay out-of-pocket costs and protect against extra charges. But Medigap also has a monthly premium.
Late-Enrollment Penalty
If you don't enroll in Part B when you first become eligible, you may face a permanent late-enrollment penalty. The penalty is calculated as a percentage of the standard Part B premium. The longer you wait, the higher the penalty.
There are exceptions. If you have health coverage through your employer and you are still working, you may have a grace period. Certain other situations also allow you to enroll without a penalty. For details about your situation, see Enrollment & Deadlines or call Medicare.
Enrollment Windows
Most people become eligible for Medicare at age 65. You can enroll in Part B during your Initial Enrollment Period. This period starts three months before you turn 65, includes the month you turn 65, and ends three months after. Enroll during this window to avoid a late-enrollment penalty.
If you miss your Initial Enrollment Period, you can enroll during the General Enrollment Period (January 1 to March 31 each year). But a penalty applies. Learn more at Enrollment & Deadlines.
Working Past 65 and Employer Coverage
If you are still working and have health coverage through your employer when you turn 65, you may delay enrolling in Part B without a penalty. Your employer coverage is primary. You can enroll in Part B when your employment ends or your coverage ends. But you must enroll right away to avoid a penalty.
This exception only applies if your employer has 20 or more employees. If your employer is smaller, Medicare is primary. Enroll in Part B on time in this case. See Working Past 65 for more about how employment affects your Medicare enrollment.
Part B and Other Medicare Options
Part B is a basic part of Original Medicare. Some people choose Medicare Advantage (Part C) instead, which is a private insurance plan alternative. If you choose Original Medicare (Parts A and B), you can also add Part D (prescription drug coverage) and a Medigap (Supplement) plan to lower your out-of-pocket costs.
Key Takeaways
- Medicare Part B covers doctor services, hospital outpatient care, preventive care, lab work, imaging, medical equipment, mental health care, and some medicines given in an outpatient setting.
- You pay a monthly premium (which may be higher if your income is above certain levels due to IRMAA), an annual deductible, and 20% coinsurance for most services.
- See a participating provider who accepts assignment to control your costs. Non-participating providers may charge you extra.
- If you don't enroll when eligible, you may face a permanent late-enrollment penalty. Exceptions apply if you have employer coverage.
- Enroll during your Initial Enrollment Period (three months before through three months after you turn 65) to avoid a penalty.
- If you work past 65 with employer health coverage, you can delay Part B enrollment. But enroll right away when that coverage ends.
- You can add Medigap and Part D to your Original Medicare to lower your out-of-pocket costs.