The answer
What are Medicare Part B excess charges?
A Medicare Part B excess charge is an extra amount a doctor can bill above the Medicare-approved rate for a service.
This happens only when a provider does not accept Medicare assignment, meaning they have not agreed to accept Medicare's approved amount as full payment. By law, that extra charge is limited to no more than 15 percent above the Medicare-approved amount, and some states ban excess charges entirely. Excess charges matter when choosing a Medigap policy (Medicare Supplement, private coverage that pairs with Original Medicare) because some plans cover them and some do not. For example, Medigap Plan G covers Part B excess charges, while Medigap Plan N does not, leaving you to pay them. Many doctors do accept assignment, so excess charges may never affect you, but if you see providers who do not, the difference between plans can matter.