CARC (Claim Adjustment Reason Code)
A CARC is the standardized code on a remit that tells you why a payer reduced or denied a payment — the single most important field for deciding whether money is recoverable.
A CARC (claim adjustment reason code) is the X12-standard code a payer puts on each adjusted line to explain why it paid less than you billed. It's the 'why' behind every denial and reduction: CO-197 for a missing authorization, CO-45 for a contractual adjustment, CO-97 for bundling, CO-29 for timely filing, and hundreds more. Every CARC rides with a group code (CO, PR, OA, PI) that says who is responsible for the amount, and CARCs are paired one-to-one with the dollars they explain, so a single line can carry several. The CARC is the field that decides your next move: some point to legitimate write-offs, many point to appealable denials, and a large share are ambiguous enough that the same code is recoverable on one claim and final on another. Reading the CARC accurately — and knowing which ones are worth working — is the core skill of denial recovery. Because CARCs are standardized across all payers, they're also what makes denial data poolable: you can rank your denials by CARC, spot the two or three codes and payers driving most of your lost dollars, and work the pile where the money actually is.
Volari classifies every CARC on every remit, separating true write-offs from denials wearing a contractual label — and files appeals only where the code and the chart say the claim is winnable.
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