Healthcare Error Code
Healthcare Insurance / Medical Billing
Claim Adjustment Reason Codes (CARC)
CO-31 | Patient cannot be identified
Industry
Healthcare
Canonical
/healthcare/error-codes/co-31/
Last Updated
Feb 25, 2026
Summary
This code indicates that the payer could not identify the patient based on the information submitted.
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What This Code Means
CO-31 is used when patient identification details do not match payer records. Accurate identification is required for claim processing. When discrepancies occur, adjudication cannot proceed. This code reflects a data matching issue rather than a coverage or service determination. It does not imply that coverage does not exist.
Where Users Usually See This Code
- Claim rejection notices
- Remittance advice
- Payer portal claim status pages
Why This Code Appears
- Incorrect patient name or identifier submitted
- Mismatch in date of birth or policy number
- Incomplete patient demographic information
What Typically Happens Next
- The claim is not processed
- Reprocessing may occur after correction
- Payment is delayed
What This Code Is Not
- It is not a non-covered service decision
- It is not a contractual adjustment
- It is not a denial of eligibility
Troubleshooting Checklist
- □ Verify patient demographic data
- □ Confirm policy identifiers
- □ Review payer data requirements
Notes And Edge Cases
Minor typographical errors can trigger this code. Payer systems may have strict matching criteria that vary by insurer.
Related Codes
8 links
- CO-16 CodeClaim lacks required information
- CO-109 CodeClaim not covered by this payer
- CO-133 CodeIncorrect provider type
- CO-61 CodeProcedure not covered for age
- CO-178 CodeClaim did not contain sufficient information
- CO-23 CodeImpact of prior payer adjudication
- CO-29 CodeTime limit expired
- CO-62 CodeNot covered for place of service
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