CARC — Claim Adjustment Reason Codes
CARCs appear in the 835 remittance advice CAS segment and tell you why the payer paid less than the billed amount — bundling, medical necessity, prior-auth gaps, timely-filing, patient responsibility, and contractual adjustments. 306 codes seeded, ordered by US search demand. Every leaf page cites the official X12 description and pairs the RARC partners typically observed on the 835. Source: X12 External Code Lists.
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Showing 2 of 306 CARCs in Duplicate.
| Rank | Code | Description (X12) | Category | US search / mo |
|---|---|---|---|---|
| #10 | CARC B13 | Previously paid. Payment for this claim/service may have been provided in a previous payment. | Duplicate | 390 |
| #17 | CARC 18 | Exact duplicate claim/service | Duplicate | 240 |
Tools for the reason codes in this directory
Bundling, unit and medical-necessity adjustments can be checked against CMS data before you work the denial.
Paired with a RARC?
Most CARCs arrive on the 835 alongside one or more Remittance Advice Remark Codes that narrow the reason. See the RARC remark-code reference for the paired explanations.