"While the usage mentioned doesn't violate the implementation guide and would be considered compliant, that coding does not seem to reflect the total explanation for $0.00 payment in that it implies an allowed amount for that service of $0.00 when the service is covered, and a responsibility for the provider to write-off the charge. The 835 is intended to accurately reflect the business of the claim. In the interest of administrative simplification, a total write-off using CAS*CO*45 is not recommended and doesn't represent an accurate business statement. The payer has an obligation to report the Claim Adjustment Reason Code and Claim Adjustment Group Code that accurately identifies the reason for the denial and the proper responsibility for the denied amount."

When the full submitted charge is sent as the CAS*CO*45 amount, the payer is reporting that the fee schedule/maximum allowable or contracted/legislated fee arrangement for the service is $0. If this is not the case, the CO*45 is not appropriate and should not be used.