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4
CO - Contractual ObligationCoding/Billing
Denial Code CO-4: Procedure Code Inconsistent with Modifier
What Does Code 4 Mean?
The procedure code is inconsistent with the modifier used, or a required modifier is missing.
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?
Incorrect modifier appended to the CPT code, or a modifier was not included when required.
How to Resolve It
- 1Review CPT and modifier coding guidelines
- 2Correct the modifier and resubmit
- 3Verify with the payer which modifier is expected