ASC facility billing operates under a distinct Medicare OPPS-adjacent payment system—packaged ancillaries, procedure-specific payment indicators, and strict device pass-through rules create unique revenue capture challenges that differ fundamentally from physician billing. VeriMedix specializes in maximizing ASC facility revenue while keeping claims fully compliant.
Ambulatory Surgery Centers bill as facilities under Medicare's ASC payment system, which is based on the Outpatient Prospective Payment System (OPPS) but uses ASC-specific payment rates that are approximately 50–60% of the Hospital Outpatient Department (HOPD) rates for most procedures. The ASC must be a Medicare-certified facility and is reimbursed for the facility fee—which includes nursing, supplies, equipment use, and most ancillary services—while the operating surgeon, anesthesiologist, and other physicians bill separately under Part B for their professional services. Understanding what is packaged (bundled) into the ASC payment versus what is separately payable is the foundational challenge of ASC facility billing.
Each CPT/HCPCS procedure assigned to the ASC setting carries an ASC Payment Indicator that determines how it is reimbursed. Indicator 'A1' means the procedure is paid at the ASC rate; 'N1' indicates it is packaged into the payment for a primary procedure (not separately payable); 'R2' means it is not paid in the ASC setting; 'K2' means it is a covered ancillary service paid separately only in the ASC context. Device-intensive procedures (those where the device cost is a significant portion of total cost) may qualify for device pass-through under HCPCS C-codes or specific device APC categories. New technology APCs (NTAPs) may also apply for qualifying technologies. CMS updates the ASC payment system annually in the OPPS/ASC final rule published each November, effective January 1.
Commercial payer contracting for ASCs is an additional layer of complexity. Unlike Medicare's fixed fee schedule, commercial payers negotiate rates that may be percentage of billed charges, case rates, or percentage of Medicare. The ASC's chargemaster must be maintained at appropriately high charge levels to ensure percentage-of-charges contracts yield adequate reimbursement. Managed care contract review, with specific attention to carve-outs for implants, high-cost drugs, and unlisted procedures, is essential. Modifier SG (ASC facility service) has been deprecated from Medicare claims but remains in use by some commercial payers; verify each payer's specific requirements for ASC facility claim submission format (UB-04 vs. 1500).
Below are commonly billed codes our certified coders manage for ambulatory surgery center practices. Always confirm payer-specific coverage and current code values.
| Code | Description | Billing note |
|---|---|---|
27447 | Total knee arthroplasty (TKA) | ASC-eligible per CMS since 2020; device-intensive; verify ASC payment indicator and implant pass-through eligibility; document device cost on claim |
66984 | Extracapsular cataract removal with insertion of intraocular lens prosthesis | Among the highest-volume ASC procedures; packaged supply costs; IOL reported as device on claim |
45378 | Colonoscopy, flexible, with or without single or multiple biopsy(ies) | APC packaged; higher-complexity GI procedures (polypectomy 45380, 45385) have higher ASC payment rates |
43239 | Upper GI endoscopy (EGD) with biopsy | Common ASC GI procedure; confirm payer coverage in outpatient setting; document medical necessity |
29881 | Arthroscopy, knee, surgical; with meniscectomy | High-volume orthopedic ASC procedure; 90-day global for professional claim; ASC facility bills separately |
52000 | Cystourethroscopy (diagnostic) | Common urology ASC procedure; verify payment indicator—may be packaged when performed with therapeutic procedure |
62321 | Injection, epidural, lumbar or sacral (including imaging guidance if performed) | High-volume pain management ASC procedure; confirm imaging component bundled with 2017 CPT changes |
C1769 | Guide wire (HCPCS device code) | Example device pass-through code; report on facility claim when device qualifies for separate ASC payment |
Our standard operating procedures for ambulatory surgery center revenue cycle management — the step-by-step workflow we follow on every claim:
These are the issues we see most often in ambulatory surgery center billing — and exactly how we resolve them:
Under ASC payment rules, most drugs, supplies, and diagnostic tests are packaged into the APC/procedure payment and not separately payable. Billing them separately results in denial or recoupment. Fix: maintain an up-to-date packaging matrix in your CDM; configure your billing system to suppress packaged items from separate billing while retaining them for chargemaster reporting.
ASC facility claims for Medicare must be submitted on UB-04. Some commercial payers accept or require CMS-1500 for ASC claims. Submitting on the wrong form results in rejection. Fix: create a payer-specific submission format matrix and configure your clearinghouse routing to match.
Device pass-through claims (C-codes) are denied when the claim lacks the device invoice, HCPCS code match to the implant used, and documentation of device use in the operative report. Fix: implement an implant log capture process at the time of surgery; route device receipts to the billing department same-day.
CMS publishes an annual list of procedures covered in the ASC setting. Performing a procedure not on the ASC-covered list for Medicare results in non-payment. Fix: maintain the current year's ASC covered procedure list in your scheduling workflow; flag any procedure not on the list for payer-specific coverage verification before scheduling.
ASCs on percentage-of-billed-charges contracts lose revenue when their chargemaster has low charge levels. Fix: benchmark charges against regional peers and update the CDM annually to ensure charges are set at levels that support adequate reimbursement under percentage-of-charges contracts.
Verimedix works inside the systems ambulatory surgery center practices already use, including:
The ASC submits a facility claim (UB-04) for the use of the facility, nursing, and packaged supplies/equipment. The physician (surgeon, anesthesiologist, assistant) submits a separate professional claim (CMS-1500) for their personal services. These are independent revenue streams billed to the same payer but processed separately.
No. Medicare no longer requires modifier SG on facility claims submitted on the UB-04. However, some commercial payers still require SG to identify ASC facility services—always check payer-specific billing guidelines.
For procedures where the device cost is substantial (e.g., joint replacement implants), the ASC reports the device using a HCPCS C-code on the facility claim. If the device qualifies for device pass-through payment under Medicare, it is reimbursed separately in addition to the APC payment for the procedure. Device offset rules may reduce the APC payment when a device offset applies.
No. The ASC facility fee does not include anesthesiologist or CRNA professional services. The anesthesia provider bills separately. The ASC may include the cost of anesthesia supplies and drugs in the facility claim as packaged items under the surgical APC.
Report the procedure with modifier -74 (discontinued outpatient procedure after anesthesia induction). Medicare pays a reduced ASC facility rate for cases discontinued after anesthesia was administered. Modifier -73 is used if the case was cancelled before anesthesia.
For bilateral procedures on the same day, the ASC bills the procedure twice with RT and LT modifiers (or modifier -50 for bilateral, per payer guidance). Medicare pays 150% of the single procedure rate for bilateral procedures (100% for the first side, 50% for the second side) when each side is documented as a separately performed procedure.
CMS updates the ASC covered procedure list annually as part of the OPPS/ASC final rule, typically published in November and effective January 1 of the following year. VeriMedix recommends reviewing the final rule each November to update your scheduling eligibility matrix and chargemaster.
Verimedix handles the entire ambulatory surgery center revenue cycle — coding, submission, denials, and A/R — so your team can focus on patients.