Reimbursement for procedures and services performed by providers is made by commercial payers such as Aetna, United Healthcare, or federal intermediaries acting on behalf of healthcare programs. Reimbursement is based on claims and documentation filed by providers using medical diagnosis and procedure codes.

Commercial payers must use standards defined by the U.S. Department of Health and Human Services (HHS) but are largely regulated state-by-state. Except for specific national mandates such as reimbursement for childbirth, commercial payers determine their own rules of medical necessity or payment and reimbursement fee schedules. Federal intermediaries are regulated as contractors by the Centers for Medicare & Medicaid Services (CMS).

Medicare reimburses physicians and other providers/suppliers for services rendered to Medicare beneficiaries on a fee-for-service (FFS) basis. CMS develops fee schedules for physicians, ambulance services, clinical laboratory services and durable medical equipment, prosthetics, orthotics and supplies.

CMS offers Medicare FFS providers, physicians, and other practitioners and suppliers a one-stop resource for all of their informational needs and interests on its Provider Center web page.