APCs or Ambulatory Payment Classifications are the United States government's method of paying for facility outpatient services for the Medicare (United States) program.
A part of the Federal Balanced Budget Act of 1997 made the Centers for Medicare and Medicaid Services create a new Medicare "Outpatient Prospective Payment System" (OPPS) for hospital outpatient services -analogous to the Medicare prospective payment system for hospital inpatients known as Diagnosis-related group or DRGs.
APCs are an outpatient prospective payment system applicable only to hospitals.
Physicians are reimbursed via other methodologies for payment in the United States, such as Current Procedural Terminology or CPTs.
Although APCs began through the federal system of Medicare, they have also been considered for adoption by state programs, such as Medicaid, and other third-party private health insurers.