CARC (claim adjustment reason code)
CARCs are a national code set maintained for X12 and used by all US health plans on remittances (X12 CARC list). Every adjustment on an ERA pairs one with a group code:
- CO (contractual obligation), PR (patient responsibility), OA (other adjustment), PI (payer-initiated reduction) (X12 group codes).
So "CO-45" means a contractual write-off because the charge exceeds the fee schedule, while "PR-2" means coinsurance the patient owes.
Many CARCs require or invite a RARC (remittance advice remark code) with the specific detail. CARC 16, for example, must be accompanied by at least one remark code. The remark code is usually where the actionable fix is (X12 RARC list).
The ones dietitians see most: 1, 2, 3 (deductible, coinsurance, copay), 45 (fee schedule), 16 (missing or invalid information), 11 (diagnosis inconsistent with procedure), 50 (not medically necessary), 96 (non-covered charge), 119 (benefit maximum reached) and 29 (filing limit expired).