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18
CO - Contractual ObligationCoding/Billing
Denial Code CO-18: Exact Duplicate Claim
What Does Code 18 Mean?
Exact duplicate claim/service. The payer has already processed an identical claim with the same information.
Group Code CO (Contractual Obligation): The provider has agreed to accept the payer's determination. The patient is generally not responsible for this amount.
Why Does This Happen?
The claim was submitted more than once with identical data.
How to Resolve It
- 1Check the original claim status before resubmitting
- 2If the original was paid, no action needed
- 3If the original was denied, correct and resubmit as a corrected claim (not a duplicate)