CO-31: Patient Cannot Be Identified as Insured

What Does CO-31 Mean?

With CO (Contractual Obligation), the CARC 31 adjustment is the provider's responsibility. The payer denied or reduced payment because of the member ID submitted on the claim does not match any active enrollee in the payer's system. The patient is not liable for this amount. If the denial is in error, the provider can correct and resubmit the claim or file an appeal with supporting documentation.

CARC 31 indicates patient cannot be identified as insured. The payer determined that the service or a portion of it does not meet coverage criteria under the patient's current plan benefits or the applicable coverage rules.

Common scenarios that trigger this adjustment include: the member ID submitted on the claim does not match any active enrollee in the payer's system; Claim submitted to wrong insurance company - patient has coverage with a different carrier; Patient's name on the claim does not match the name on file with the payer (maiden vs married name, legal name change). The group code paired with CARC 31 determines who bears the financial responsibility — CO places it on the provider as a contractual obligation, OA indicates a coordination of benefits or other payer adjustment, PR shifts it to the patient.

Common Causes

How to Resolve

1. Review the remittance details Examine the CO-31 adjustment and any accompanying RARC codes to identify the specific reason for the denial.
2. Identify the root cause Determine which issue applies: incorrect member ID or subscriber number, wrong payer, name mismatch, among others.
3. Correct the claim Address the identified issue — update the claim data in your billing system to resolve the patient cannot be identified as insured problem.
4. Resubmit the corrected claim Submit the corrected claim following the payer's resubmission guidelines. Include any supporting documentation that addresses the denial reason.
5. Appeal if the original claim was correct If the patient is enrolled but the payer cannot find them, appeal with the insurance card, enrollment confirmation, and correct member demographics. Contact the payer to update their enrollment records.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-31:

How to Prevent CO-31

• Copy/scan insurance cards at every visit
• Verify eligibility electronically before services
• Confirm member ID, name, and DOB match payer records
• Update patient insurance data at each visit
• Train front desk staff on thorough insurance verification

Also Filed As

The same CARC 31 may appear with different Group Codes:

Related Denial Codes