CO-4Modifier missing or invalid CO-11Diagnosis / procedure mismatch CO-15Authorization issue CO-16Missing information CO-18Duplicate claim CO-22Coordination of benefits CO-27Coverage lapsed CO-29Timely filing expired CO-40Service not covered CO-45Exceeds fee schedule CO-50Not medically necessary CO-97Bundled service CO-107Not a covered charge CO-109Wrong payer CO-167Diagnosis not covered CO-222Exceeds maximum allowable CO-236NCCI edit conflict CO-242Provider out of network CO-256Not payable per contract All codesThe full reference list