What Medicare Part B Covers

Medicare Part B is the part of Original Medicare that pays for doctor visits, outpatient care, and certain medical equipment and services. It covers what you need when you are not admitted to a hospital overnight — the visits to your primary care doctor, specialist appointments, lab tests, X-rays, and procedures done in a clinic or office setting.

Part B also covers preventive services like annual wellness visits, cancer screenings, and vaccines. It pays for durable medical equipment such as wheelchairs, walkers, and oxygen supplies. Ambulance transport, mental health counseling, and physical therapy are covered too, though some have limits on how many visits you can have per year.

Part B does not cover dental care, vision exams, hearing aids, or long-term care in a nursing home. It also does not cover prescription drugs — that is what Part D is for. If you want coverage for those gaps, you can buy a Medigap plan or join a Medicare Advantage plan instead of staying in Original Medicare.

Key Takeaways

  • Part B covers doctor visits, specialist appointments, lab work, X-rays, and outpatient procedures, but not dental, vision, or hearing care.
  • You pay a monthly premium for Part B, a yearly deductible, and then 20 percent of the cost of most services after the deductible is met.
  • Your doctor must accept Medicare assignment for you to pay the lower Part B rates; if they do not, you may owe more.
  • Part B enrollment happens when you turn 65, and missing the important date without a good reason can result in a permanent penalty on your premium.

How Much Part B Costs

Part B has three layers of cost: the monthly premium, the yearly deductible, and coinsurance. The monthly premium is deducted from your Social Security check (or paid directly if you do not receive Social Security). The standard premium amount changes each year; it was $164.90 per month in 2024, but yours may be higher if your income is above a certain threshold.

Once you have paid your yearly deductible — $240 in 2024 — Medicare begins to pay its share. For most Part B services, you then pay 20 percent of the approved amount, and Medicare pays 80 percent. There is no yearly cap on how much you can spend out of pocket for Part B services, which is why many people buy a Medigap plan to cover the 20 percent coinsurance.

If your doctor does not accept Medicare assignment, you may be charged more than the approved amount. Always ask your doctor's office whether they accept Medicare assignment before your visit. If they do not, ask what they will charge you — it could be significantly more than the standard 20 percent coinsurance.

When Your Doctor Must Accept Medicare Rates

Doctors who are Medicare participating providers agree to accept the Medicare-approved amount as full payment (except for your deductible and coinsurance). This is called "accepting assignment." Most doctors do this because it simplifies billing and keeps their patient base stable.

If your doctor is a participating provider, you pay only your deductible and 20 percent coinsurance. The doctor bills Medicare directly, and Medicare sends the payment to them. You should receive an Explanation of Benefits (EOB) in the mail showing what Medicare paid and what you owe.

Some doctors are non-participating providers. They can still see Medicare patients, but they are not required to accept the Medicare-approved amount. They can charge up to 15 percent more than the approved amount — this is called "balance billing." If a non-participating doctor charges you more, you are responsible for the difference. Always confirm your doctor's status before scheduling.

How to Use Your Part B Benefits

When you go to a doctor's office or outpatient clinic, bring your Medicare card. The office staff will verify your coverage and may ask you to pay your deductible upfront if you have not met it yet. After your visit, the provider bills Medicare. Medicare processes the claim and sends you an EOB explaining what they paid and what you owe.

For some services — like imaging, certain surgeries, or mental health visits — your doctor may need to request prior authorization from Medicare before the appointment. This means the doctor asks Medicare in advance whether the service is medically necessary. If Medicare denies the request, you have the right to appeal. Your doctor's office can usually handle this step, but ask them to confirm they will submit the authorization request.

Keep copies of your EOBs and any bills you receive. If you are billed for something you think Medicare should have paid, you can file an appeal. You have 120 days from the date on the EOB to appeal a decision.

Part B Enrollment and Penalties

You are automatically enrolled in Part B when you turn 65 if you are already receiving Social Security benefits. If you are not yet receiving Social Security, you must sign up for Part B during your initial enrollment period, which is the three months before the month you turn 65, the month you turn 65, and the three months after.

If you miss this window and do not have a good reason — such as still being covered by an employer health plan — you will owe a permanent penalty. The penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. This penalty stays on your premium for as long as you have Part B, even if you enroll years later.

If you are still working and covered by your employer's health plan at 65, you may be able to delay Part B without penalty. You must enroll within eight months of losing that coverage. Contact Social Security or Medicare to confirm your situation before your coverage ends.

Part B and Other Coverage

If you have a Medigap policy, it works alongside Part B to cover some of the costs you would otherwise pay yourself. Medigap plans are sold by private insurance companies and cover things like your deductible, coinsurance, and copayments. They do not cover services that Part B does not cover.

If you are in a Medicare Advantage plan (Part C) instead of Original Medicare, you do not use Part B the same way. Medicare Advantage plans are run by private insurers and include Part A and Part B coverage bundled together, usually with lower out-of-pocket costs but a smaller network of doctors. You still pay the Part B premium, but your cost-sharing and coverage rules are different.

If you are still working and have employer coverage, that plan is primary and pays first. Medicare is secondary and pays only what your employer plan does not cover. Once you retire and lose employer coverage, Medicare becomes primary.

What to Ask Your Doctor About Part B

Before your appointment, call your doctor's office and ask: "Do you accept Medicare assignment?" and "Will you submit the claim to Medicare for me, or do I need to?" Ask what your out-of-pocket cost will be based on your deductible status. If you need a procedure or specialist referral, ask whether prior authorization is required and whether the office will request it.

After your visit, review your EOB carefully. Check that the services listed match what you received. If you see a charge you do not recognize or think is wrong, contact your doctor's office first to clarify. If you believe Medicare made an error, you can file an appeal through Medicare directly.

Frequently Asked Questions

Do I have to enroll in Part B when I turn 65?

You are automatically enrolled if you are receiving Social Security. If you are not yet receiving Social Security, you must enroll during your initial enrollment period (three months before, the month of, and three months after your 65th birthday) or face a permanent premium penalty. If you are still covered by an employer plan, you may delay enrollment without penalty.

What happens if my doctor does not accept Medicare assignment?

They can charge up to 15 percent more than the Medicare-approved amount, and you are responsible for the difference. Always ask whether your doctor accepts assignment before scheduling. If they do not, ask what they will charge you so you can decide whether to see them or find a participating provider.

Can I appeal if Medicare denies a service?

Yes. You have 120 days from the date on your Explanation of Benefits to file an appeal. You can file online through Medicare.gov, by mail, or by phone. Your doctor's office may help you gather medical records to support your appeal.

Does Part B cover physical therapy?

Yes, but there are limits. Medicare covers physical therapy when it is medically necessary and ordered by your doctor. Your doctor may need to request prior authorization. Some therapy may be limited to a certain number of visits per year, depending on your condition.

What is the difference between Part B and a Medicare Advantage plan?

Part B is Original Medicare — you pay a premium and then 20 percent coinsurance after your deductible. Medicare Advantage is a private plan that includes Part A and Part B coverage with different cost-sharing rules and usually a smaller network of doctors. You still pay the Part B premium either way.