Coding Audits: What Physician-Owned Practices Miss Most Often

Coding audits are the most misunderstood engagement in RCM. Many practice owners think of them as a compliance exercise, something you do to avoid an audit. Coding audits do reduce compliance risk. They also routinely find substantial recoverable revenue. Both matter.

The errors we see most often.

Under-coding office visits. The most common error, especially in high-volume primary care and specialty practices, is billing 99213 when the documentation supports 99214, or 99214 when the documentation supports 99215. The difference per visit is significant. Over a year, on a full patient panel, it adds up to five figures or more.

Missing modifier 25. When a significant, separately identifiable E/M service is performed on the same day as a procedure, modifier 25 unbundles the E/M for separate reimbursement. Practices routinely omit it, either because the biller does not know the rule or because the documentation does not clearly support "significant, separately identifiable." The fix is often documentation training, not just coding.

Bundled procedures billed as global. Procedures that could be billed separately under modifier 59 (or the more specific X modifiers) get bundled by default. The revenue lost per claim is modest. The revenue lost across a year of claims is substantial.

Wrong place of service codes. Office procedures billed with the wrong POS code get paid at the wrong rate. Common mistakes: hospital-based practices billing office POS, or practices with multiple locations using the same POS across all sites.

Missing HCPCS J-codes for administered drugs. Injectables and infusions have specific J-codes for the drug itself, separate from the administration code. Missing the drug code means missing reimbursement for the drug.

Incorrect ICD-10 specificity. Payers routinely deny or downcode claims with insufficient ICD-10 specificity. Coding to the highest applicable specificity is often the difference between full reimbursement and reduced reimbursement.

Post-op period modifiers. Modifier 24 (unrelated E/M during a post-op period), 25, 57 (decision for surgery), and 79 (unrelated procedure during post-op) all unbundle care during global periods when used correctly. They get omitted often.

How coding audits work.

A structured coding audit reviews a random or targeted sample of claims. Documentation is compared against billed codes. Errors are identified in both directions: undercoded claims (recoverable revenue) and overcoded claims (compliance risk to correct).

The output is a specific list of coding corrections, with dollar amounts and compliance implications, plus recommendations for training or process changes to prevent the same errors going forward.

When a coding audit pays for itself.

Practices that have never had a systematic coding audit, or have not had one in the last 3 years, almost always find enough recoverable revenue to fund the audit multiple times over. Surgical specialties, high-volume office practices, and practices with complex modifier requirements have the highest yield.

Schedule a Free Revenue Diagnostic Call to discuss whether a coding audit fits your practice.

Related reading

• The Five Most Common Denial Codes and How to Recover From Them
• How to Reduce Medical Claim Denials: 7 Strategies That Work in 2026