Yes, while excess charges are not common, Missouri, like most states, allows them. Thus, your physician may bill for excess charges if they do not accept Medicare assignment. Some Medicare Supplement plans Missouri residents have available do not cover Medicare excess charges. For example, Medicare Supplement Plan N in Missouri does not cover these charges. Excess charges are an additional cost of up to 15% over the Medicare-approved service cost from a physician who does not accept Medicare assignment. But again, the number of doctors who do not accept Medicare assignment is minimal. You will likely never face excess charges. To avoid these charges, consult with your physician before receiving any medical services.