Denial Code Library
Plain-English, biller-practical guides to the CARC codes that cost independent practices the most — what each means, why it fires, and exactly how to get the money.
- CO-16 — Claim/service lacks information or has submission/billing error(s)
- CO-197 — Precertification / authorization absent
- CO-50 — Not deemed a medical necessity by the payer
- CO-29 — Timely filing limit expired
- CO-97 — Payment included in another service's allowance (bundling)
- CO-151 — Payment adjusted — information doesn't support this many/frequency of services
- CO-18 — Exact duplicate claim/service
- CO-22 — Care may be covered by another payer per coordination of benefits
- CO-4 — Procedure code inconsistent with modifier (or required modifier missing)
- CO-45 — Charge exceeds fee schedule/contracted arrangement
- CO-109 — Claim/service not covered by this payer — send to the correct payer
- CO-252 — An attachment/other documentation is required to adjudicate
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