Medical Billing Denial Codes: Complete CARC and RARC Reference

Medical billing denial codes are standardized reason codes issued by payers to explain why a claim was adjusted, reduced, or denied. Every code maps to a specific cause, from timely filing violations to bundling rules to missing documentation, and each one requires a different corrective action. Effective denial management starts with reading the CARC and RARC codes on the remittance advice and working the claim from the correct resolution path.

This reference covers all Claim Adjustment Reason Codes (CARC) and Remittance Advice Remark Codes (RARC) used across Medicare, Medicaid, and commercial payers. Each entry includes the official definition, the billing scenarios most likely to trigger it, and the steps required to correct, resubmit, or appeal the claim. Codes tied to medical necessity often depend on whether a waiver of liability was collected under modifier GA before the service was rendered.