Medicare billing happens between your doctor and Medicare, not between you and Medicare

When you receive care from a doctor, hospital, or other healthcare provider who accepts Medicare, that provider sends the bill directly to Medicare. You do not send anything to Medicare yourself. The provider submits a claim with details about the service you received, the date, and the cost. Medicare then reviews the claim and pays the provider their share. Your role is to understand what happens after that — what you might owe, what paperwork you should watch for, and what to do if something looks wrong.

The process works differently depending on which part of Medicare you have and which type of provider treated you. A hospital bills differently than a doctor's office. A specialist bills differently than your primary care doctor. Understanding the basic flow helps you spot errors and know what bills are legitimate.

Key Takeaways

  • Providers who accept Medicare bill Medicare directly; you do not submit the claim yourself.
  • Medicare sends you an Explanation of Benefits (EOB) for each claim, showing what Medicare paid and what you owe.
  • You may owe a copay, coinsurance, or deductible depending on the type of service and your coverage.
  • Providers must give you an estimate before certain procedures, and you can ask questions if a bill seems too high.
  • If a provider does not accept Medicare, you pay them upfront and then request reimbursement from Medicare yourself.

What happens after your provider sends the claim to Medicare

Once your provider submits a claim to Medicare, the claim goes into a processing system. Medicare checks whether the service is covered under your plan, whether the provider is in-network (if you have Medicare Advantage), and whether the charge is reasonable. This review usually takes two to four weeks, though it can take longer for complex claims.

Medicare then sends you an Explanation of Benefits (EOB) — a document that shows what your provider billed, what Medicare approved, what Medicare paid, and what you owe. The EOB is not a bill; it is a record of what happened. Your provider may send you a separate bill for your share (copay, coinsurance, or deductible) after they receive Medicare's payment.

If you have Original Medicare (Part A and Part B), Medicare pays 80 percent of approved charges for most services after you meet your deductible. You pay the remaining 20 percent. If you have Medicare Advantage, your plan pays based on your plan's rules, which may include copays or coinsurance amounts set by your plan.

Understanding what you owe after Medicare pays

Your out-of-pocket cost depends on the type of service, your deductible status, and your coverage type. For a doctor's office visit under Original Medicare, you typically pay 20 percent of the approved amount after you meet your annual Part B deductible (which is $240 in 2024, though this amount changes yearly). For hospital stays, the rules are different — you pay a deductible per stay under Part A, then Medicare covers most costs.

If you have a Medigap policy (supplemental insurance), that policy may cover some or all of your 20 percent share, depending on which Medigap plan you chose. If you have Medicare Advantage, your out-of-pocket costs follow your plan's structure, which your plan documents spell out.

Providers cannot bill you for the difference between what they charged and what Medicare approved — that is called balance billing, and it is illegal for providers who accept Medicare. If a provider tries to bill you for that difference, you can report them to Medicare.

How to read your Explanation of Benefits

Your EOB shows several key pieces of information. The "Provider" line tells you who billed Medicare. The "Service Date" is when you received care. The "Charge" is what the provider billed. The "Approved Amount" is what Medicare decided was reasonable — this is often lower than the charge. The "Medicare Paid" line shows what Medicare sent to the provider. The "You Owe" line shows your responsibility.

Read the EOB carefully to make sure the service date, type of service, and provider name are correct. If something does not match what you remember, contact your provider or Medicare to ask about it. Do not assume an error will fix itself — Medicare processes thousands of claims daily, and mistakes do happen.

Keep your EOBs. They are your record of what Medicare covered and what you paid. If you need to file a complaint, appeal a decision, or track your deductible progress, your EOBs are the documents you will need.

What to do if you receive a bill you do not recognize

If a provider sends you a bill and you do not remember receiving that service, or if the amount seems wrong, contact the provider's billing department first. Ask them to explain what service was billed and when it occurred. Bring your insurance card and any paperwork from that visit. Sometimes bills are sent for services you did receive but forgot about, or for services that were bundled together.

If the provider cannot explain the bill or if you still believe it is wrong, contact Medicare. You can call 1-800-MEDICARE (1-800-633-4227) and ask them to review the claim. Have your EOB and the provider's bill in front of you when you call. Medicare can tell you whether the claim was processed correctly and whether you actually owe that amount.

If a provider who accepts Medicare is trying to bill you for more than your share (the copay, coinsurance, or deductible), that is balance billing and is not allowed. Report it to Medicare or to your state's insurance commissioner.

Providers who do not accept Medicare

Some doctors and providers do not accept Medicare. If you see a provider who does not accept Medicare, you pay them the full bill upfront. You then submit the claim to Medicare yourself, along with an itemized receipt from the provider. Medicare will review it and send you reimbursement for their share — usually 80 percent of the approved amount after your deductible.

Before you see a provider who does not accept Medicare, ask them for an estimate in writing. Ask whether they will submit the claim to Medicare for you or whether you will need to do it. Some non-participating providers will submit on your behalf; others will not. Knowing this in advance helps you plan for out-of-pocket costs.

Requesting an estimate before a procedure

For certain procedures and services, you have the right to ask your provider for an estimate of what you will owe. This is especially important for scheduled procedures like surgery, imaging, or lab work. Ask your provider's billing department for an estimate at least a few days before your appointment. They should give you an estimate based on your coverage type and deductible status.

Keep in mind that an estimate is not a may provide — your actual bill may differ if the procedure takes longer than expected or if additional services are needed. But an estimate gives you a ballpark figure so you are not surprised by the bill later.

Frequently Asked Questions

Do I need to do anything when my provider bills Medicare?

No. Your provider handles the billing. Your job is to watch for the Explanation of Benefits in the mail, check it for accuracy, and pay any bill you receive from your provider for your share. Keep the EOB for your records.

What if Medicare denies my claim?

Medicare will explain the reason on your EOB. Common reasons include the service not being covered, the provider not being in-network (for Medicare Advantage), or the service being deemed not medically necessary. You can appeal the decision by following the instructions on your EOB, usually within 180 days.

Can my provider bill me before Medicare makes a decision?

No. Providers who accept Medicare must wait for Medicare to process the claim before billing you for your share. If a provider bills you before Medicare has paid, contact their billing department and ask them to wait.

What is the difference between a charge and an approved amount?

The charge is what the provider billed. The approved amount is what Medicare decided is reasonable for that service in your area. Medicare only pays based on the approved amount, even if the provider charged more. You are responsible for your percentage of the approved amount, not the full charge.

How long does it take to receive my EOB?

Most EOBs arrive within two to four weeks of the service date, though complex claims can take longer. If you have not received an EOB within six weeks, contact Medicare to check on the status of your claim.