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CO-224 Denial Code: Patient Identity Theft Suspected

CO-224 means the patient's identification has been compromised by identity theft, and the payer needs identity verification before it will process this and future claims. It is a hold on the member's ID, not a coding error.

Quick facts

Code
CO-224 (CARC 224)
Status
Active In use since June 1, 2008.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The claim is not paid until identity is verified. The amount should not be billed to the patient while the identity question is open.
Official description
Patient identification compromised by identity theft. Identity verification required for processing this and future claims.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-224 means

CARC 224 says the patient identification has been compromised by identity theft, and identity verification is required for processing this and future claims. The payer has flagged the member’s ID, usually because the member reported identity theft or the payer detected suspicious use of the ID.

Two parts of the text matter. First, this claim will not be paid until identity is verified. Second, future claims for this member will face the same hold, so the issue will keep repeating until it is resolved.

Medical identity theft can mean that someone else used the member’s insurance to get care. That creates billing risk and patient safety risk, because the wrong person’s information may end up in the chart.

Common causes

  • Member reported identity theft to the payer, which then flagged the ID.
  • Payer detected unusual activity, such as services in several states on the same day.
  • Stolen or shared insurance card presented at registration.
  • Member ID reissued after a breach, with claims still arriving under the old ID.

How to fix it

  1. Pause billing for this member under this payer until identity is sorted out, and do not send the balance to the patient.
  2. Review registration records: the photo ID and insurance card copies, signatures, and demographics captured at the visit.
  3. Contact the payer to learn its identity verification process and whether a new member ID was issued.
  4. Ask the patient to contact the payer if the payer requires member verification.
  5. If identity is confirmed, update the member ID in box 1a if it changed and resubmit or request reprocessing as the payer instructs.
  6. If the person treated was not the member, involve compliance, correct the medical record, and do not bill the member’s coverage.

How to prevent it

  • Check a government-issued photo ID along with the insurance card at registration, especially for new patients.
  • Compare demographics against prior visits and question mismatches.
  • Scan and keep ID and card images in the patient record.
  • Run real-time eligibility at every visit; a changed member ID can signal a reissue after a breach.
  • Train front-desk staff to escalate suspected identity problems privately and respectfully.

See eligibility and COB denials for more on patient-identification issues that block claims.

Remark codes that may appear with CO-224

  • N382 (Missing/incomplete/invalid patient identifier.): The patient identifier on the claim is missing, incomplete, or invalid, often because a new member ID was issued.
  • N202 (Alert: Additional information/explanation will be sent separately.): The payer will send identity verification instructions separately.
  • CO-31 (Patient cannot be identified as our insured.): The patient could not be identified as the payer's insured, without any identity-theft flag.
  • CO-140 (Patient/Insured health identification number and name do not match.): The patient's ID number and name do not match, which can be a data-entry issue.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): General missing or invalid claim information, including patient identifiers.

CO-224 FAQ

Does CO-224 mean my patient committed fraud?

No. It means the payer believes the member's identity has been compromised, which often makes the patient the victim. Handle it carefully and without accusation.

How do I get a CO-224 claim paid?

Follow the payer's identity verification process, which may involve the patient contacting the payer and the provider confirming identity documents from the visit. After verification, the payer may reprocess or ask you to resubmit with a new member ID.

What if the person treated was not the real member?

Do not resubmit under the member's ID. Correct the medical record, involve your compliance team, and follow the payer's instructions. The actual person treated is a separate billing matter.