A doctor who accepts Medicare assignment cannot charge more than Medicare’s approved amount for a covered service. Some other doctors may charge a limited extra amount. The rules depend on how the doctor participates in Original Medicare.

Providers Who Accept Assignment

A provider who accepts assignment agrees to accept the Medicare-approved amount as full payment for a covered service. You may owe the deductible and coinsurance, but the provider cannot add an excess charge. The provider must also submit the Medicare claim.

Non-Participating Providers

A non-participating provider may accept assignment for an individual service. If the provider does not, you may have to pay the full bill upfront and wait for Medicare to pay its share back to you.

In many cases, the provider cannot charge more than 15% above the Medicare-approved amount. This ceiling is called the limiting charge. Some services are not subject to that limit, and some states impose stricter rules.

Medigap Plans F and G cover Part B excess charges under standardized federal benefits. Plan N does not.

Here is an example with made-up figures. Suppose Medicare’s payment amount for a participating doctor is $100. For a non-participating doctor, the approved amount is generally 95% of that, or $95. The 15% limit uses that $95 amount, so the maximum bill would be $109.25 where the federal limit applies. If you have met your deductible, Medicare pays 80% of $95, or $76. You would owe $33.25 before supplemental insurance. If that doctor accepts assignment for this service, you would owe $19 instead. Medicare explains assignment and limiting charges.

The 15% rule is not a general cap on equipment bills or entirely noncovered services. A practice may charge a separate concierge fee for extras Medicare does not cover. It cannot use that fee to charge more for a covered service when assignment rules prohibit it.

Providers Who Opt Out

A provider who opts out of Medicare generally uses a private contract, and Medicare generally does not pay. Limited emergency or urgent-care exceptions can apply, such as care for someone without an existing private contract with that provider. Medicare charge limits do not apply to care under a private contract.

Before a non-emergency visit, ask whether the doctor accepts Medicare assignment for the specific service and request an estimate of your share.

Ask the billing office to identify whether an estimated charge is deductible or coinsurance, a permitted excess charge, or a separate noncovered service. Those categories determine whether Medicare or a Medigap policy can pay it.

Medicare policy sources last checked: October 8, 2026.