Revenue Cycle Management · Denial Reference

Medical Denial Codes:
Your Complete Reference

Every CARC denial code explained — with root causes, appeal strategies, and resolution tips written by RCM professionals, for RCM teams.

What are denial codes?

Denial codes are standardized codes used by payers to explain why a claim was denied, reduced, or adjusted. They help billing and revenue cycle teams understand what went wrong and what action is needed to resolve the issue. These codes appear on Explanation of Benefits (EOBs) or Electronic Remittance Advice (ERAs).

CO — Contractual ObligationAmounts the provider cannot bill the patient due to contractual agreements with the payer.

OA — Other AdjustmentDenials or reductions that don't fall under standard categories.

PR — Patient ResponsibilityDenied amount is the patient's responsibility — copays, deductibles, or non-covered services.

PI — Payer Initiated ReductionAdjustments made by the payer based on internal policies or processing rules.

MA / B / M — Medicare / SupplementalMedicare remittance advice remark codes and supplemental denial codes for specific Medicare billing scenarios.

Code	Type	Category	Description

Medical Denial Codes:Your Complete Reference

What are denial codes?

Medical Denial Codes:
Your Complete Reference