Medicare Part B excess charges are an occasional additional expense that can occur on top of the Medicare-approved amount for a specific service. These charges are applicable only when your healthcare provider accepts Medicare but chooses not to accept Medicare assignment. While not all states permit excess charges, most do, and Hawaii is one of them. In cases where your provider does not accept Medicare assignment, they may bill you for an extra fee of up to 15% for the services rendered. However, it’s essential to note that most healthcare providers do accept Medicare assignment, making excess charges relatively uncommon.