Ambulatory Surgical Center Billing Cheat Sheet (2026)
ASC billing is facility billing, separate from the surgeon's professional claim, and it is governed by the ASC covered procedures list and a fixed payment methodology. The denials come from procedures not on the list, multiple-procedure discounting, and the discontinued-procedure rules.
Quick reference for ambulatory surgical center billers. Last updated .
Top Ambulatory Surgical Center CPT Codes & 2026 Medicare Allowables
| Code | Description | Non-Facility | Facility | Total RVU |
|---|---|---|---|---|
| 29881 | Knee arthroscopy with meniscectomy | $515.71 | $515.71 | 15.44 |
| 43239 | Upper GI endoscopy with biopsy | $418.85 | $123.58 | 12.54 |
| 45378 | Diagnostic colonoscopy | $378.10 | $164.67 | 11.32 |
| 66984 | Cataract extraction with intraocular lens insertion | $462.60 | $462.60 | 13.85 |
| 64483 | Lumbar transforaminal epidural injection | $264.87 | $99.53 | 7.93 |
| 11042 | Debridement, subcutaneous tissue, 20 sq cm or less | $132.60 | $55.78 | 3.97 |
| 49083 | Abdominal paracentesis with imaging guidance | $284.24 | $92.85 | 8.51 |
| 11600 | Skin lesion excision, malignant, 0.5 cm or less | $198.40 | $108.55 | 5.94 |
| 52000 | Diagnostic cystoscopy | $215.77 | $71.14 | 6.46 |
National 2026 Medicare Physician Fee Schedule estimates (total RVU multiplied by the conversion factor). These are adjusted by state locality. See the per-state table on the Ambulatory Surgical Center billing services page.
Modifiers That Prevent Ambulatory Surgical Center Denials
The ASC facility service, required by payers that still distinguish the facility line from the professional line.
A procedure discontinued after the patient was prepared but before anesthesia was induced, which reduces the facility payment.
A procedure discontinued after anesthesia induction or after the procedure started, which pays the facility at a higher reduced rate than 73.
A distinct procedure separate from another that NCCI would otherwise bundle within the same session.
Laterality or bilateral status on the facility claim where the payer requires it for adjudication.
A screening colonoscopy that converted to a therapeutic procedure, adjusting the patient cost share on the facility claim.
Top Ambulatory Surgical Center Denials → Quick Fix
Confirm the procedure is on the payer's ASC covered procedures list before scheduling. A non-listed procedure is not a covered ASC facility service.
The primary procedure pays at full ASC rate and additional procedures at the reduced multiple-procedure rate. Rank the procedures correctly on the claim.
Append modifier 73 (before anesthesia) or 74 (after induction) for a discontinued case. Billing the full facility fee for a discontinued procedure is a coding-accuracy denial.
The ASC bills the facility fee, the surgeon bills the professional fee separately. Submitting the professional service on the facility claim duplicates and denies.
Bill separately payable implants per the payer's ASC implant policy with the invoice or required documentation; bundled or undocumented implants are denied.
NCCI Bundling Watch-Outs
Code pairs from this specialty's set that carry NCCI edits. Billing both without a justified modifier triggers a bundling denial.
| Code | Bundles With | Rationale |
|---|---|---|
| 29881 | 01250 | Anesthesia service included in surgical procedure |
| 29881 | 01320 | Anesthesia service included in surgical procedure |
| 43239 | 00520 | Anesthesia service included in surgical procedure |
| 43239 | 00731 | Anesthesia service included in surgical procedure |
| 45378 | 00731 | Anesthesia service included in surgical procedure |
| 45378 | 00732 | Anesthesia service included in surgical procedure |
| 66984 | 00142 | Anesthesia service included in surgical procedure |
| 66984 | 00144 | Anesthesia service included in surgical procedure |
Documentation That Holds Up on Appeal
That the procedure is on the payer's ASC covered list and the facility service with modifier SG where required.
The ranking of procedures so the primary pays full and additional at the multiple-procedure reduced rate.
Whether the case stopped before anesthesia (73) or after induction or start (74), with the clinical reason.
The implant, invoice, and the payer's separately-payable policy criteria.
The screening intent and the therapeutic conversion, supporting modifier PT and the correct patient cost share.
Revenue Ambulatory Surgical Center Practices Leave on the Table
Scheduling procedures not on the ASC covered list, which are not payable as facility services.
Mis-ranking multiple procedures so discounting is applied to the wrong line.
Billing discontinued cases at the full facility fee instead of with modifier 73 or 74.
Not separately billing payable implants per the payer's ASC implant policy.
Ambulatory Surgical Center Billing FAQ
How is ASC payment structured?
A fixed facility payment per procedure on the ASC covered procedures list, separate from the surgeon's professional fee. Procedures off the list are not covered ASC facility services.
How does multiple-procedure discounting work?
The highest-weighted procedure pays at the full ASC rate and additional procedures at a reduced multiple-procedure rate. The claim has to rank procedures correctly or the discount is misapplied.
Modifier 73 or 74 for a discontinued case?
73 when the procedure is stopped after preparation but before anesthesia induction, 74 when stopped after induction or after the procedure began. 74 pays the facility at a higher reduced rate than 73.
Can the ASC bill the surgeon's service?
No. The ASC bills the facility fee and the surgeon bills the professional fee on a separate claim. Combining them duplicates the service and denies.
Stop Losing Ambulatory Surgical Center Revenue to Preventable Denials
Our AAPC-certified ambulatory surgical center coders apply every rule on this sheet to your claims. Call 888-701-6090 for a free billing assessment.