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POS 24: Ambulatory Surgical Center

POS 24 is the CMS place of service code for Ambulatory Surgical Center, defined as a freestanding facility, other than a physician's office, where surgical and diagnostic services are provided on an ambulatory basis. On Medicare professional claims paid under the physician fee schedule, POS 24 takes the facility rate (Pub. 100-04, chapter 26).

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: CMS Place of Service code set: CMS page last modified February 17, 2026; code table updated May 2, 2024 (effective August 1, 2024). Next CMS release: no fixed schedule (CMS posts new place of service codes on its code set page, usually months before Medicare's effective date).

Place of service code
24
Medicare fee schedule rate
Facility rate
Pub. 100-04, chapter 26, section 10.5
In effect since
Before 2003
Reported on
Professional claims
CMS-1500 item 24B or the 837P
Setting group
Ambulatory surgical and birthing centers

CMS definition of POS 24

A freestanding facility, other than a physician's office, where surgical and diagnostic services are provided on an ambulatory basis.

CMS Place of Service code set, Ambulatory Surgical Center

POS 24 is one of the long-standing codes that CMS lists without a date, meaning it was in effect on or before January 1, 2003 (Medicare Claims Processing Manual, Pub. 100-04, chapter 26, section 10.5).

Facility or non-facility rate for POS 24

Medicare pays a physician fee schedule service billed with this code at the facility rate. The facility rate carries a smaller practice-expense component than the non-facility rate, because in a facility setting the facility, not the practitioner, bears the cost of the room, the staff and most supplies; where the facility is a Medicare provider it is paid for those costs on its own claim.

Chapter 12, section 20.4.2 of the Medicare Claims Processing Manual lists this setting as “Medicare-participating ambulatory surgical center (ASC) for a HCPCS code included on the ASC approved list of procedures; Medicare-participating ASC for a procedure not on the ASC list of approved procedures with dates of service on or after January 1, 2008.” on its facility list. The rule behind the list is that the code reflects where the beneficiary received the face-to-face service, except that services to a registered hospital inpatient or outpatient are paid at the facility rate wherever the encounter took place.

Practitioners who operate in a Medicare-participating ambulatory surgical center report POS 24. POS 11 is allowed for ASC-based work only when the physician's office shares the ASC's location and meets the distinct-entity criteria, and the service was performed in the office suite (chapter 26, section 10.5).

Not every service has two rates: when the facility and non-facility amounts are the same, as they are for the professional component of a diagnostic test, the place of service does not change the payment. Outpatient therapy and comprehensive outpatient rehabilitation facility services are always paid at the non-facility rate.

Medicare instructions for this setting

Special considerations for Ambulatory Surgical Centers (Code 24)

When a physician/practitioner furnishes services to a patient in a Medicare-participating ambulatory surgical center (ASC), the POS code 24 (ASC) shall be used.

NOTE: Physicians/practitioners who perform services in an ASC shall use POS code 24 (ASC). Physicians/practitioners are not to use POS code 11 (office) for ASC based services unless the physician has an office at the same physical location of the ASC, which meets all other requirements for operating as a physician office at the same physical location as the ASC – including meeting the “distinct entity” criteria defined in the ASC State Operations Manual that precludes the ASC and an adjacent physician office from being open at the same time -- and the physician service was actually performed in the office suite portion of the facility.

See Pub 100-07, Medicare State Operations Manual, Appendix L - Guidance for Surveyors: Ambulatory Surgical Centers for a complete set of applicable ASC definitions, basic requirements, and conditions of coverage. It is available at the following link: http://www.cms.gov/manuals/Downloads/som107ap_l_ambulatory.pdf

Quoted from the Medicare Claims Processing Manual, Pub. 100-04, chapter 26, section 10.5.

Denials when POS 24 does not fit the claim

A place of service that conflicts with the procedure, the patient's registration or the payer's policy comes back with one of three codes. Claim adjustment reason code 5 means the procedure code or bill type is inconsistent with the place of service; reason code 58 means the payer considers the setting inappropriate or invalid for the service; and remark code M77 marks a missing, incomplete, invalid or inappropriate place of service. Medicare returns a line whose POS is missing, unassigned or incompatible with a site-specific procedure as unprocessable with CARC 16 and M77, so the fix is a corrected claim rather than an appeal (Pub. 100-04, chapter 26, section 10.6).

Where QuickIntell fits with place of service

QuickRCM covers eligibility, claim readiness, denials, posting and A/R with configurable automation and human review, the stage where the place of service code is checked against the setting, the registration and the modifier before the claim goes out, and where CARC 5, CARC 58 and M77 denials are worked.

See QuickRCM for claim readinessSee QuickCode for coder reviewBook a meeting

Frequently asked questions

What is place of service code 24?

POS 24, Ambulatory Surgical Center, is defined by CMS as follows: A freestanding facility, other than a physician's office, where surgical and diagnostic services are provided on an ambulatory basis. POS 24 is one of the long-standing codes that CMS lists without a date, meaning it was in effect on or before January 1, 2003 (Medicare Claims Processing Manual, Pub. 100-04, chapter 26, section 10.5). It sits in the ambulatory surgical and birthing centers group with POS 25.

Does POS 24 pay the facility or the non-facility rate?

The facility rate. Medicare Claims Processing Manual, Pub. 100-04, chapter 26, section 10.5 designates POS 24 F, so a physician fee schedule service billed with it is paid at the facility rate, the lower practice-expense amount paid when the setting rather than the practitioner carries the cost of space, staff and supplies. Chapter 12, section 20.4.2 lists it as "Medicare-participating ambulatory surgical center (ASC) for a HCPCS code included on the ASC approved list of procedures; Medicare-participating ASC for a procedure not on the ASC list of approved procedures with dates of service on or after January 1, 2008." on the facility list. Services whose two rates are equal, such as the professional component of a diagnostic test, pay the same either way (chapter 12, section 20.4.2).

When should a claim use POS 24?

Practitioners who operate in a Medicare-participating ambulatory surgical center report POS 24. POS 11 is allowed for ASC-based work only when the physician's office shares the ASC's location and meets the distinct-entity criteria, and the service was performed in the office suite (chapter 26, section 10.5).

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The definition is reproduced from the CMS Place of Service code set; the Medicare rate and instructions are from Pub. 100-04, chapters 12 and 26. Medicaid and commercial plans publish their own place of service rules. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.