1. A health care provider billing method utilized with a patient who has health insurance provided by a health insurance entity, where the health care provider and health insurance entity have entered into a billing contract whereby the health care provider agrees to bill a patient covered by the health insurance entity at contracted rates which may be lower than full rates established by the health care provider for services given to the patient, and which precludes the health care provider from directly balance billing the patient for the difference between the contracted rates and the full rates, except when a separate payment entity, other than the health insurance entity is liable to the patient for a covered event related to the services, the billing method comprising: the health care provider entering into a billing contract with a patient, where the billing contract includes a provision that enables the health care provider to effect compensatory invoicing, allowing for collection of monies from a separate payment entity and/or the patient, who has received monies from a separate payment entity other than the health insurance entity, the difference between the contracted rates and the full rates; providing medical services to the patient: billing the health insurance entity for the services at the contracted rate; identifying a separate payment entity other than the health insurance entity or patient who may be liable to the patient for payment related to the provided services due to the covered event; and effecting compensatory invoicing, thereby billing the identified, payment entity and/or the patient who has received monies from an identified payment entity for the difference between the contracted rates and the full rates.