CO-4: The procedure code is inconsistent with the modifier used.

Why it fires

• The modifier is not applicable to the procedure code's category, such as a bilateral modifier on a code that is inherently bilateral
• The modifier was outdated or retired for this code as of the date of service
• The wrong modifier was selected from a similar-looking set, such as 25 versus 59, or an RT/LT typo

Corrective actions, ranked

1. 1

   Verify modifier validity

   Check CPT/HCPCS modifier guidelines to confirm this modifier is appropriate for this specific code.

2. 2

   Correct the modifier

   Fix the modifier to the correct, supported one and resubmit as a corrected claim.

3. 3

   Update your charge master or scrubber

   If this is a recurring pairing error, fix the coding software or charge template causing it.

Is it worth appealing

Not an appeal candidate. Correct the modifier and resubmit rather than appealing a coding error.

Modifiers named in these corrective actions

The corrective actions for CO-4 point at these modifiers. Check when each one is appropriate before you append it.

• Modifier 59Distinct procedural service
• Modifier 25Significant, separately identifiable evaluation and management service
• Modifier LTLeft side
• Modifier RTRight side

Other denial codes to check

Codes that share a remark code with this one, or that are reported under the same group code.

• CO-45Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.
• CO-97The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.
• CO-16Claim/service lacks information or has submission/billing error(s).
• CO-11The diagnosis is inconsistent with the procedure.
• OA-18Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)
• CO-29The time limit for filing has expired.

See every CARC in the dataset