Medical Coding Audit Guide: How to Audit Your Practice's Coding

Regular coding audits are one of the most effective tools for protecting your practice from overpayments, underpayments, and payer audits. Here's how to do them right.

Why Coding Audits Matter

The Office of Inspector General (OIG) publishes an annual Work Plan outlining areas of heightened scrutiny. Practices that don't self-audit regularly are far more likely to have problems if they're selected for an external audit by Medicare, Medicaid, or a commercial payer.

Beyond compliance, audits identify revenue opportunities — practices typically find 5–15% revenue improvement from fixing coding errors discovered in self-audits.

Types of Coding Audits

• Prospective (pre-bill) audit: Review claims before submission — highest accuracy but resource-intensive
• Concurrent audit: Review during the billing cycle — balances accuracy and efficiency
• Retrospective audit: Review after claims are submitted — useful for identifying patterns and training needs

What to Include in a Coding Audit

• Sample of 20–30 records per provider, per quarter
• Mix of E/M visits (new and established), procedures, and preventive care
• Cases across your most-billed CPT codes
• Cases flagged for denial patterns
• Cases with high-risk modifiers (25, 59, 50, etc.)

Step-by-Step Audit Process

1. Select your audit sample (random + targeted)
2. Pull the clinical documentation and assigned codes
3. Review documentation to determine what level of service was actually supported
4. Compare documented level to billed level
5. Calculate accuracy rate: (correct codes ÷ total codes reviewed) × 100
6. Document findings by provider and code category
7. Report results and develop corrective action plan
8. Reaudit in 90 days to confirm improvement

Acceptable Accuracy Benchmarks