Healthcare Error Code
Healthcare Insurance / Medical Billing
Claim Adjustment Reason Codes (CARC)

CO-31 | Patient cannot be identified

Industry
Insurance
Canonical
/insurance/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
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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.

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Related Codes

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