CO-224 denial code
Patient identification compromised by identity theft
How to fix it
Do not resubmit routinely. Contact the payer's special investigations unit and follow their process.
How to prevent it
Verify identity at registration with photo ID for new patients.
In practice
A claim returns CO-224 indicating the patient's identity has been flagged as compromised. The patient attended, the service was real, and the account is now frozen.
The payer has identified suspected identity theft affecting this member, which suspends normal processing. Resubmitting the claim through ordinary channels will not clear it and may add to the flagged activity.
The route is the payer's special investigations unit and whatever verification process they specify. That process exists to separate legitimate claims from fraudulent ones, and cooperating with it is what gets the claim paid.
What sits behind it
Medical identity theft is genuinely damaging to the patient, well beyond the billing consequences. Fraudulent claims under their identity can corrupt their medical record, exhaust their benefits and create clinical risk if false information influences later care.
Providers occupy a difficult position here. The practice may have delivered legitimate care to the real patient and still be caught inside an investigation, which is why documentation of identity verification at registration matters more than it appears to.
Photo identification at registration for new patients is the practical control, and it protects the patient as much as the practice. It is also the evidence that supports your claim when an investigation asks who was actually treated.
Related codes
Terms used here — Eligibility Verification · HIPAA · Denial
How we handle it — Eligibility Verification · Denial Management · Patient Support
Primary sources
The rules behind CO-224, at the bodies that publish them.
- Remittance Advice Remark Codes (RARC) (opens in a new tab)
X12 — The remark codes that qualify a CARC on an ERA. Reading the RARC is usually what tells you whether a denial is appealable.
- CMS-1500 claim form standards (opens in a new tab)
National Uniform Claim Committee — Maintainer of the CMS-1500 professional claim form and its data element definitions, plus the provider taxonomy code set.
- NPI Registry (NPPES) (opens in a new tab)
Centers for Medicare & Medicaid Services — Public lookup and management for National Provider Identifiers. A stale NPPES record is a quietly common cause of enrollment and claim rejections.
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-224
No. Routine resubmission will not clear the flag and may add to the activity under investigation. Contact the payer's special investigations unit and follow the verification process they specify, which exists precisely to separate legitimate claims from fraudulent ones.
Considerably more than the billing. Fraudulent claims under their identity corrupt their medical record, consume their benefits, and can create clinical risk if false diagnoses or medications influence later treatment. The billing issue is the smallest part.
By verifying identity with photo identification at registration for new patients and documenting that it was done. That protects the patient from having their identity used and gives the practice evidence of who was actually treated when an investigation asks.
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