How CARC and RARC Code Sets Are Maintained

Governance of the CARC and RARC Code Sets#

CARC and RARC are national standard code sets named under HIPAA for use on the X12 835 remittance advice. Because they are standards, no single payer can invent its own reason codes for these transactions — they must use the published values. This standardization is what makes automated, payer-agnostic denial processing possible.

Who maintains them.

• Claim Adjustment Reason Codes (CARC) are maintained by a national code-maintenance committee and published by X12. The list is updated on a regular cycle (typically three times a year), with codes added, modified, deactivated, or marked for retirement.
• Remittance Advice Remark Codes (RARC) are maintained by the Centers for Medicare & Medicaid Services (CMS) and likewise published and updated on a regular cycle.
• The Washington Publishing Company (WPC) has historically published the canonical, public lists of both code sets along with their descriptions.

Why maintenance matters for software. Because codes are added and retired on a schedule, any system that classifies denials from CARC/RARC must keep its code tables current. A retired or newly added code that the software does not recognize can cause a denial to be misrouted or missed. Mature RCM platforms version their code tables to the official release dates.

Group codes are fixed. Unlike the CARC/RARC lists, the Group Codes (CO, PR, OA, PI) are a small, stable set defining financial responsibility. They almost never change, and they are the first thing a denial-classification rule reads to decide who owes the money.

Practical takeaway: building denial automation on the *standard* CARC/RARC/Group-code values — rather than free-text remarks — is what lets one rule set work across hundreds of payers. The standardization is the whole point.