Ambulatory Surgical Center (ASC)

An ASC is defined as an entity that operates exclusively for furnishing outpatient surgical services to patients. To receive coverage of and payment for its services under this provision, a facility must be certified as meeting the requirements for an ASC and enter into a written agreement with CMS.

Two Types of ASCs

  1. Independent: Not part of a provider of services or any other facility
  2. Hospital: ASC under common ownership, licensure or control of a hospital

Access the below ASC related information from this page.

Covered ASC Facility Services

To view a complete listing of approved codes, see the CMS ASC Payment Rates - Addenda webpage. The covered surgical procedures are listed in Addendum AA and covered ancillary services are listed in Addendum BB. The listing is updated at least annually by CMS.

Payment Inclusions

Service Inclusion
Nursing services, services of technical personnel and other related services All services with covered procedures furnished by nurses and technical personnel who are employees of ASC

Patient's care provided by orderlies and other personnel
Use by the patient of the ASC facilities Operating and recovery rooms, patient preparation areas, waiting rooms and other areas used by patient or offered for use by patient's relatives with surgical services
Drugs, biologicals, surgical dressings, supplies, splints, casts, appliances and equipment All supplies and equipment commonly furnished by ASC with surgical procedures

Drugs and biologicals that cannot be self-administered are exceptions

Coverage for surgical dressings is limited to primary dressings; i.e., therapeutic and protective coverings applied directly to lesions on the skin or on openings to the skin required as the result of surgical procedures. Items such as Ace bandages, elastic stockings and support hose, Spence boots and other foot coverings, leotards, knee supports, surgical leggings, gauntlets, and pressure garments for arms and hands are generally used as secondary coverings and are not covered as surgical dressings. Surgical dressings usually are applied first by a physician and are covered as "incident to" a physician's service in a physician's office setting. In ASC setting, such dressings are included in facility's services. When patient on a physician's order obtains surgical dressings from a supplier, e.g., a drugstore, surgical dressing is covered under Part B. The same policy applies in case of dressings obtained by patient on a physician's order following surgery in an ASC; dressings are covered and paid as a Part B service by local Part B contractor, included in definition of facility services
Diagnostic or therapeutic items and services Items and services furnished by ASC staff with covered surgical procedures. ASCs perform simple tests just before surgery, primarily urinalysis and blood hemoglobin or hematocrit, which are generally included in their facility charges. To the extent that such simple tests are included in ASC's facility charges, they are considered facility services; however, under the Medicare program, diagnostic tests are not covered in laboratories independent of a physician's office, rural health clinic, or hospital unless the laboratories meet regulatory requirements for conditions for coverage of services of independent laboratories. Therefore, diagnostic tests performed by ASC other than those generally included in facility's charge are not covered under Part B as such and are not billed to Medicare Administrative Contractor (MAC) as diagnostic tests. If ASC has its laboratory certified as meeting regulatory conditions, the laboratory itself bills for tests performed. ASC may make arrangements with an independent laboratory or other laboratory, such as a hospital laboratory, to perform diagnostic tests it requires prior to surgery. In general, however, necessary laboratory tests are done outside ASC prior to scheduling of surgery, since test results often determine whether beneficiary should even have the surgery done on an outpatient basis in first place
Administrative, recordkeeping and housekeeping items and services Items such as scheduling, cleaning, utilities, rent, etc.
Blood, plasma, platelets, etc., except those to which blood deductible applies Covered procedures limited to those not expected to result in extensive loss of blood, in some cases, blood or blood products are required

Usually blood deductible results in no expenses for blood or blood products being included under this provision; however, where there is a need for blood or blood products beyond deductible, they are considered ASC facility services and no separate charge is permitted to beneficiary or program
Materials for anesthesia Includes anesthetic itself, and any materials, whether disposable or reusable, necessary for its administration
Intraocular lenses (IOLs) Implantable devices, with exception of those devices with pass-through status under OPPS

Dressings applied during or after surgical procedures included in facility fee


Covered Ancillary Items and Services

Ancillary items and services integral to a covered surgical procedure and for which separate payment to the ASC is allowed include the below.

  • Brachytherapy sources
  • Certain implantable items that have pass-through status under OPPS
  • Certain items and services that CMS designates as contractor-priced, including by not limited to, procurement of corneal tissue
  • Certain drugs, biologicals and radiology services for which separate payment is allowed under OPPS

Not Part of Facility Fee

  • Physicians' services
    • Includes services of anesthesiologists administering or supervising administration of anesthesia, beneficiary's recovery from anesthesia and routine pre- or post-operative services such as office visits, removal of stiches, changing of dressings, etc.
  • Sale, lease, or rental of Durable Medical Equipment (DME) for home use
  • Prosthetic devices
  • Non-implantable prosthetic devices
  • Ambulance services
  • Leg, arm, back and neck braces
  • Artificial legs, arms and eyes
  • Services of independent laboratories


Two primary costs are involved in the surgical procedures performed in an ASC.

  1. Physician's professional services for performing procedure
  2. Cost of services furnished by facility where procedure was performed

The professional fee is paid to the physician and payment for facility costs are paid to the ASC.

Claim Submission

ASCs must not report separate line items, HCPCS Level II codes, or any other charges for procedures, services, drugs, devices, or supplies that are packaged into the payment allowance for covered surgical procedures. The allowance for the surgical procedure itself includes these other services or items. Covered ancillary items and services, such as pass-through devices, brachytherapy sources, separately payable drugs and biologicals and radiology procedures, should be billed on the same claim as the related ASC surgical procedure.

Place of service (POS) 24 indicates an ASC, a freestanding facility, other than a physician's office, where surgical and diagnostic services are provided on an ambulatory basis.

When a patient is in a Part A Skilled Nursing Facility (SNF) stay, any service provided by an ASC, during that time, is not paid as a Part B claim.

ASCs are required to report the TC modifier when billing for facility charges associated with HCPCS codes that have both a technical component and a professional component under the Medicare Physician Fee Schedule (MPFS).

Terminated Surgical Procedures Documentation

Payment is made when a surgical procedure is terminated due to the patient having medical complications which would put them at risk to continue with the procedure. ASC claims that involve a terminated surgery must be accompanied by an operative report that specifies all the below.

  • Reason for termination of surgery
  • Description of services performed
  • Description of supplies provided
  • Services not performed that would have been if surgery had not been terminated
  • Supplies that would have been provided if surgery had not been terminated
  • Time spent in each stage (e.g., pre-op, operative, post-op)
  • Time that would have been spent in each of these stages if surgery had not been terminated
  • CPT codes for procedures that were scheduled to be performed

Two modifiers are associated with terminated procedures.

  • Modifier 73: Procedure terminated before administration of anesthesia
    • Allows 50 percent
  • Modifier 74: Procedure terminated after administration of anesthesia
    • Allows full payment

Modifier 53 is for physician-use only and is not used by ASCs.

Implanted Devices

ASC surgery allowed amount includes the costs of implanted devices. Sometimes the device is being provided at no or partial cost to the ASC. To indicate this, use modifier FB.

  • Modifier FB: Device provided at no cost or will be fully credited
    • Device provided with partial credit of 50% or higher of cost



Last Updated Dec 09 , 2023

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