COReferenceCurrentVerified Aug 15, 2026Group Code CO
Contractual Obligation
AR Guide interpretation
What this group code means
The adjustment is the payer's contractual obligation — typically the difference between the billed charge and the contracted rate, or an amount the payer will not pay per the provider contract. This amount is not billable to the patient.
AR Guide interpretation
Common usage
- Contractual write-offs and fee schedule adjustments
- Denials where the payer is not liable per the contract
- Never billed to the patient
Reading the remittance advice: Note
The group code tells you who is responsible for the adjustment amount. Combine it with the CARC and any RARC on the line to understand exactly why the amount adjusted and what to do next.