A provider that accepts Medicare assignment must bill Medicare first, accept Medicare's allowed amount as full payment, and cannot balance-bill you for the difference
When a doctor or hospital accepts Medicare assignment, they sign an agreement with Medicare to follow specific rules. The most important rule is this: they bill Medicare directly, accept whatever Medicare pays as payment in full for that service, and cannot charge you the difference between what Medicare pays and what they normally charge. You pay only your copay, coinsurance, or deductible — nothing more.
This is different from a provider who does not accept assignment. Those providers can bill you for the full amount Medicare does not cover, a practice called balance billing. Accepting assignment protects you from surprise bills.
Key Takeaways
- A provider accepting assignment must submit the claim to Medicare themselves and cannot bill you for any amount above Medicare's allowed charge.
- You are responsible only for your Part B deductible, coinsurance (usually 20 percent), and copays — not for any difference between the provider's usual fee and Medicare's payment.
- Providers who accept assignment must give you a written notice before treatment if they believe Medicare will deny the claim, so you can decide whether to proceed.
- You can check whether a specific doctor or hospital accepts Medicare assignment by calling them directly or searching the Medicare provider directory online.
How billing works when a provider accepts assignment
The provider submits the claim to Medicare on your behalf. Medicare reviews it, determines the allowed amount for that service, and pays its share — usually 80 percent of the allowed amount for Part B services. The provider receives that payment directly from Medicare and cannot ask you to pay the difference between their normal fee and what Medicare paid.
Your responsibility is limited to the patient cost-sharing amounts: your annual Part B deductible (if you have not met it), coinsurance (typically 20 percent of the allowed amount), and any copays the service requires. The provider cannot charge you anything beyond these amounts.
What providers must tell you before treatment
If a provider who accepts assignment believes Medicare will deny or not cover a service, they must give you a written notice before you receive the service. This notice, called an Advance Beneficiary Notice (ABN), explains why they think Medicare will not pay and tells you what you may owe if Medicare denies the claim.
You then decide whether to go ahead. If you sign the ABN and Medicare denies the claim, you may owe the provider. If you do not sign, the provider cannot bill you if Medicare denies it. This rule protects you from unexpected bills for services Medicare does not cover.
The difference between assignment and non-assignment
| Accepts Assignment | Does Not Accept Assignment |
|---|---|
| Submits claim to Medicare | You submit the claim or provider submits it but may not |
| Accepts Medicare's allowed amount as full payment | Can charge you the full difference between their fee and Medicare's payment |
| You pay only copay, coinsurance, deductible | You pay copay, coinsurance, deductible, plus balance bill |
| Must give ABN if service may not be covered | Not required to give ABN |
How to learn about your doctor accepts assignment
The simplest way is to call the provider's office and ask directly: "Do you accept Medicare assignment?" They will tell you yes or no. You can also search the Medicare Provider Directory at Medicare.gov. Enter the provider's name and location, and the directory will show whether they accept assignment.
If you are looking for a new provider, always ask about assignment before scheduling. If your current provider does not accept assignment and you want to avoid balance billing, you may need to find a different provider in your area who does.
What happens if a provider violates assignment rules
If a provider who accepts assignment balance-bills you anyway — charging you more than your copay, coinsurance, and deductible — you can report them to Medicare. Call 1-800-MEDICARE or file a complaint online at Medicare.gov. Medicare investigates violations and can impose penalties, including removing the provider from the Medicare program.
Keep copies of all bills and explanation of benefits statements. If you receive a bill that looks wrong, compare it to what Medicare says you owe on your Explanation of Benefits (EOB). Your EOB shows exactly what Medicare paid and what you are responsible for.
Assignment and different types of Medicare coverage
Assignment rules explore to all Medicare providers — those in Original Medicare (Part A and Part B), Medicare Advantage plans, and Medigap-supplemented plans. However, the details vary slightly. In Original Medicare, the assignment rules described here explore directly. In Medicare Advantage plans, your plan contract sets the rules, but plans must still prevent balance billing for in-network providers.
If you have a Medigap policy, your supplemental insurance may cover some or all of your coinsurance and deductible, but only if the provider accepts assignment. This is another reason to confirm assignment status before treatment.
Frequently Asked Questions
Can a provider accept assignment for some patients but not others?
No. Providers who accept Medicare assignment must accept it for all Medicare patients for all services. They cannot choose which patients or which claims to accept assignment on. If they accept assignment, the rules explore to every Medicare claim they submit.
What if I go to an out-of-network provider?
Out-of-network providers are not required to accept assignment. They can balance-bill you for the difference between their fee and Medicare's allowed amount. If you use an out-of-network provider, ask first whether they accept assignment. If not, ask what they will charge you above Medicare's payment.
Does accepting assignment mean the provider accepts my insurance plan?
No. Accepting Medicare assignment means the provider accepts Medicare. They may not accept your Medigap plan, Medicare Advantage plan, or other insurance. Always confirm that the provider accepts both Medicare and your specific plan before scheduling.
What if Medicare denies a claim and I signed an ABN?
If you signed an Advance Beneficiary Notice and Medicare denies the claim, you may owe the provider for that service. The ABN told you this was a possibility. If you did not sign the ABN, the provider cannot bill you if Medicare denies it — they absorb the cost.
Can a provider who accepts assignment charge me a fee to submit my claim?
No. Providers who accept assignment cannot charge you a fee to file the claim with Medicare. Submitting claims is part of their agreement with Medicare. Any fee for paperwork or administrative work would be a violation of assignment rules.