ASC coding is the facility-level coding process for ambulatory surgery centers that assigns CPT and HCPCS codes to procedures performed at the ASC, applied to the UB-04 facility claim to generate the APC-based facility payment from Medicare and payer-contracted rates from commercial insurers. ASC facility coding is distinct from the physician’s professional coding for the same procedure. Both bill for the same surgical encounter under separate claim forms, payment systems, and coding standards.

What is APC packaging and why is it a compliance issue?

APC packaging is the CMS rule that certain services provided with a primary ASC procedure most drugs, medical supplies, recovery room, certain ancillary services are included in the APC fixed rate and cannot be billed as separate line items. Billing packaged services separately is an overpayment that triggers refund liability and compliance exposure. The packaged services list is updated annually and the cost threshold for drug packaging changes each year. ASC billing teams must verify current packaging status rather than relying on prior year determinations.

How are implants billed in ASC coding?

Implants are reported on the UB-04 using revenue code 0278 with the HCPCS code for the specific device and the actual acquisition cost from the supplier invoice. Reporting above actual acquisition cost is an overpayment regardless of list price. Certain high-cost implants qualify for pass-through payment, a separate payment above the APC rate while on the current pass-through list. Pass-through eligibility expires after two to three years when the cost is incorporated into the APC rate. Invoice verification before claim submission is the process control that prevents implant cost reporting compliance failures.

What does the OIG look for when auditing ASCs?

Recurring OIG ASC audit priorities include procedures billed to Medicare that are not on the covered procedures list, implant costs reported above actual acquisition price, packaged services billed separately, modifier 59 applied to NCCI pairs without supporting documentation, and statistical outlier billing in high-value procedure categories. The OIG Work Plan is published annually and identifies the current year’s specific priorities. ASCs that align their internal audit program with Work Plan priorities address the highest-risk areas before an external audit identifies them.

How often should an ASC conduct an internal coding audit?

ASC internal coding audits should be conducted quarterly at minimum, sampling 10 to 20 cases per major procedure category. High-volume, high-value categories orthopedics, spine, ophthalmology, pain management warrant quarterly audit coverage given their revenue density and OIG audit profile. Cases should be randomly selected within each procedure category. Findings should be documented, categorized, and reported to compliance leadership with specific case examples and process correction recommendations. Audit findings of systematic overcoding require compliance counsel assessment of the 60-day overpayment rule before any refund action is taken.

What is the 60-day rule and when does it apply to ASC coding findings?

The 60-day rule requires that identified Medicare and Medicaid overpayments be reported and refunded within 60 days of identification. When an ASC internal audit identifies a systematic overcoding or billing error that produced overpayments, the compliance officer and legal counsel must assess whether the 60-day rule applies before any action is taken. Failure to report and refund identified overpayments within 60 days can convert an inadvertent coding error into a False Claims Act liability. The proactive internal audit that identifies the overpayment gives the ASC control over the response timeline, an external OIG audit does not.

ASC Coding Compliance: Avoid OIG Audit Triggers in 2026