Ambulatory Payment Classification
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 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.
Source: Wikipedia — Ambulatory Payment Classification (CC BY-SA 4.0)