CO-199 denial code
Revenue code and procedure code do not match
How to fix it
Correct the revenue code to one valid for the procedure and resubmit.
How to prevent it
Maintain a validated revenue-code-to-procedure mapping in the charge master.
In practice
A hospital outpatient claim pairs a laboratory procedure code with a revenue code designated for radiology. The claim returns CO-199 for an incompatible pairing.
Institutional claims carry both a revenue code identifying the department and a procedure code identifying the service, and payers validate that the two describe the same thing.
Correcting the revenue code to one valid for the procedure resolves the claim. Where the pairing came from the charge master rather than from claim entry, every charge built on that entry carries the same defect.
What sits behind it
The charge master is where these originate and where they have to be fixed. A single mismapped entry produces the denial on every claim using it, so correcting individual claims addresses a fraction of the exposure while leaving the source generating more.
Annual code updates are the recurring trigger. When a procedure code changes, the revenue code mapped to it in the charge master does not update automatically, and the pairing that was valid in December becomes invalid in January.
Because this is institutional billing, it rarely affects professional claims, which carry no revenue codes. Practices billing both should expect the denial only on the institutional side and check the charge master rather than the coding staff.
Related codes
Terms used here — CPT Code · Charge Capture · Claim Scrubbing
How we handle it — Claims Management · Revenue Cycle Management · Practice Analytics
Primary sources
The rules behind CO-199, 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-199
Almost always in the charge master. A single mismapped entry produces the denial on every claim that uses it, so correcting claims individually addresses a small share of the exposure while the source continues generating more.
Because when a procedure code changes, the revenue code mapped to it in the charge master does not update automatically. A pairing valid in December becomes invalid in January, and nothing flags it until claims start denying.
No. Revenue codes appear on institutional claims only, so practices billing both sides should expect this on the institutional claims and investigate the charge master rather than reviewing coder decisions.
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