CARC Code Directory
Claim Adjustment Reason Codes
CARCs explain why payment or responsibility differs from the billed claim. CO, PR, OA, and PI are separate group codes, so always read the CARC together with the group code and any RARCs before taking action.
Quick Answer
CARC (Claim Adjustment Reason Code) codes are standardized codes used by insurance payers on remittance advice to explain why a claim was adjusted or denied. CARC codes are grouped into four categories: CO (Contractual Obligation), PR (Patient Responsibility), OA (Other Adjustment), and PI (Payer Initiated). Every denied or adjusted claim includes at least one CARC code.
Key Takeaways
CARC codes explain why a claim payment differs from the billed amount.
CO codes are payer-side adjustments that cannot be billed to the patient.
PR codes indicate patient responsibility — deductible, coinsurance, or copay.
OA codes are informational or administrative adjustments.
CARC codes are always accompanied by RARC codes for additional detail.
Step-by-Step
Locate the CARC code on the ERA/EOB
The CARC code appears in the claim adjustment segment of the electronic remittance advice (ERA) or the adjustment section of the patient EOB.
Identify the code group (CO, PR, OA, PI)
The group prefix tells you who is responsible: CO = contractual/payer, PR = patient, OA = other, PI = payer initiated.
Read the accompanying RARC code(s)
RARC codes provide additional detail about the specific issue. Always read CARC and RARC together for full context.
Determine the resolution action
Based on the CARC/RARC combination, determine whether to correct the claim, appeal the denial, write off the adjustment, or bill the patient.
Common Mistakes
Billing the patient for a CO (contractual) adjustment — this is not allowed for in-network providers.
Ignoring the RARC code — it contains critical detail about what went wrong.
Filing an appeal when a corrected claim would resolve the issue.
Not differentiating between CO-45 (contractual write-off) and an actual denial.
FAQ
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