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    Ambulatory Payment Classification

    The Medicare grouping system that determines hospital outpatient payment amounts under OPPS, analogous to MS-DRGs for inpatient.

    Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed May 9, 2026

    Definition

    Ambulatory Payment Classifications (APCs) are the unit of payment under the Medicare Hospital Outpatient Prospective Payment System (OPPS), established by the Balanced Budget Act of 1997 and effective August 2000. CMS groups outpatient procedures with similar clinical characteristics and resource use into APCs and pays a single bundled amount per APC, with status indicators that determine whether the service is separately payable, packaged into another APC, or excluded.
    What the regulation says
    OPPS rules are issued annually in the OPPS Final Rule (calendar-year cycle). 42 CFR 419 governs the system. CMS publishes the APC list and status indicators in OPPS Addendum B.

    What this means in practice

    APC assignment plus pass-through status (TPT) determines the outpatient economics of a new device. Many MedTech launch strategies hinge on securing a favorable APC and, where eligible, transitional pass-through payment.

    Examples

    • A hospital performs an outpatient surgical procedure, such as a colonoscopy with biopsy. Medicare uses the assigned APC to determine the bundled payment the hospital receives for all services related to that procedure.
    • When a new MedTech device is used in an outpatient setting, its financial viability for hospitals often depends on whether the procedure it enables is assigned to a well-reimbursed APC or qualifies for a separate transitional pass-through payment.
    • If a physician's office performs a service that is typically an outpatient hospital procedure, the payment structure will not be based on an APC, as APCs are specific to the Medicare Hospital Outpatient Prospective Payment System (OPPS).
    Common pitfalls
    • •Assuming an inpatient NTAP equivalent exists in OPPS, it does not; the outpatient analog is TPT.
    • •Missing the annual OPPS comment window (June-September) for APC reassignment requests.

    Frequently asked questions

    Ambulatory Payment Classifications group and pay for services under the Medicare Hospital Outpatient Prospective Payment System (OPPS), while MS-DRGs perform the analogous grouping function for inpatient stays under the Inpatient Prospective Payment System; a device or procedure moving from inpatient to outpatient care shifts from one payment logic to the other entirely. Because OPPS bundles many ancillary services into a single APC payment per encounter, a new device's outpatient economics depend heavily on which APC it falls into and whether its costs are packaged or separately payable.

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    Sources

    3 sources

    Sources support the definition or relevant regulatory context, not necessarily every claim on this page. Each is graded against our source-tier hierarchy so you can see what rests on binding law versus commentary.

    Official citation replacements checked: . Medicare documents support Medicare coding, coverage or payment context, not every payer policy or CPT editorial procedure. Citation replacement does not change the full term review date.

    Tier 1Binding law and standards· 2Tier 2Regulator guidance and consensus· 1
    Link health: 2 verified 1 unchecked· last checked 2026-06-20
    CMS·1eCFR·2
    1. 1
      CMS, Hospital OPPS
      Tier 2 Verified
      CMScms.gov
    2. 2
      42 CFR 419
      Tier 1 Verified
      eCFRecfr.gov
    3. 3
      42 CFR 419.31: Ambulatory payment classification system
      Tier 1 Unchecked
      eCFRecfr.gov

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