POS 24 — Ambulatory Surgical Center (ASC)
Services in an ambulatory surgical center
Important: POS code usage depends on the specific service, payer policy, and clinical setting. Always verify payer-specific POS requirements. The information on this page is for educational purposes only and does not guarantee payment. Consult the official CMS POS Code Set, payer provider manuals, and current coding guidelines for authoritative guidance.
POS Description
POS 24 is used for services furnished in an ambulatory surgical center (ASC). An ASC is a freestanding facility that performs surgical procedures on an outpatient basis.
Plain English Explanation
When a patient has surgery at a freestanding surgery center (not a hospital), the surgeon bills POS 24. The ASC also bills for the facility costs.
Typical Healthcare Settings
Freestanding ambulatory surgical center, outpatient surgery center, endoscopy center (in some cases).
Documentation Expectations
Document the procedure performed, the patient's pre-operative evaluation, informed consent, operative report, and post-operative disposition. Document the medical necessity of the procedure and the ASC setting.
Common Denial Scenarios
- CO-50 (not medically necessary)
- CO-97 (bundling)
- CO-16 (incorrect POS)
- CO-11 (diagnosis inconsistent with procedure)
- CO-55 (service not covered in ASC setting).
Modifier Considerations
Modifier 50 for bilateral procedures. Modifier 51 for multiple procedures. Modifier 59 for distinct procedures. Modifier 26 for professional component of diagnostic services in an ASC.
Telehealth Considerations
Telehealth is not applicable to ASC services. ASC procedures are in-person.
Payer-Specific Considerations
Medicare has a list of approved ASC procedures (ASC-covered procedures list). Not all procedures are covered in an ASC. Medicare pays the facility fee under the ASC payment system. Professional fees are paid separately under MPFS.
Professional vs Facility Billing
Professional claims (CMS-1500) bill the surgeon's service with POS 24. Facility claims (UB-04) bill the ASC's facility costs under the ASC payment system. Both professional and facility claims use POS 24.
Common Mistakes
- Using POS 24 for hospital outpatient surgery (should use POS 22). Billing procedures not on the Medicare ASC-covered list. Not coordinating professional and facility claims. Using POS 24 for procedures not approved for ASC setting.
Always Verify
POS 24 usage depends on the specific service, payer policy, and clinical setting. Always verify payer-specific POS requirements and consult the official CMS POS Code Set, payer provider manuals, and current coding guidelines.
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