best biller - we have several OON clients. For some, we bill the insurance company as a courtesy to the patients. We bill the insurance companies whatever the doctor charges. The insurance company decides how much it will pay for those charges, and sends that payment directly to the patient. For others, we provide a fee slip so they can bill the insurance company on their own. In both cases, we bill the patient directly for however much they did not pay at the time of service.