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CO-199 Denial Code: Revenue and Procedure Code Mismatch

CO-199 means the revenue code and the procedure code on the claim line don't match. It appears on institutional (UB-04 / 837I) claims when the HCPCS or CPT code isn't a valid or expected pairing with the revenue code under the payer's edits.

Quick facts

Code
CO-199 (CARC 199)
Status
Active In use since October 31, 2006.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The facility is responsible for the coding error. The amount isn't billable to the patient.
Official description
Revenue code and Procedure code do not match.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-199 means

CARC 199 reads “Revenue code and Procedure code do not match.” Institutional claims report both a revenue code (FL 42 on the UB-04), which describes the department or type of service, and a HCPCS or CPT code (FL 44), which describes the specific service. Payers run edits that check whether the two belong together. When they don’t, the line is denied.

This is a facility coding and chargemaster problem. It’s almost always fixed by correcting the line and resubmitting.

Example: a hospital outpatient drug is billed with a pharmacy revenue code that the payer’s edits don’t accept for that HCPCS drug code, which requires a different revenue code for drugs with detailed coding. The line denies CO-199 until the revenue code is corrected.

Common causes

  • Chargemaster errors, where an item is linked to the wrong revenue code.
  • Payer-specific pairing rules that differ from Medicare’s.
  • Code set updates that changed allowed pairings or created new codes.
  • Manual line entry mistakes.
  • Services moved between departments without updating revenue code mapping.
  • Therapy, drug, and supply lines where revenue code rules are strict.

How to fix it

  1. Identify the line on the ERA and the revenue code and HCPCS code billed.
  2. Check the payer’s guidelines for the correct revenue code for that service.
  3. Submit a corrected claim with type of bill frequency code 7 (replacement), or follow the payer’s process for line-level corrections.
  4. Update the chargemaster so future claims are right.
  5. Appeal only if the pairing was valid under the payer’s own rules.

How to prevent it

  • Audit the chargemaster at least annually and after code set updates.
  • Load payer-specific revenue code rules into your claim scrubber.
  • Review high-volume denials for recurring pairings. The Claims Validator can check claims before submission.
  • Coordinate with department leads when new services or supplies are added. See preventable denials.

Specialty notes

Hospital outpatient departments, SNFs, home health agencies, and outpatient therapy billed on institutional claims see this code most. Behavioral health facilities billing partial hospitalization or intensive outpatient programs must use the revenue codes the payer designates for those programs.

Remark codes that may appear with CO-199

  • M50 (Missing/incomplete/invalid revenue code(s).): The revenue code is missing, incomplete, or invalid.
  • M51 (Missing/incomplete/invalid procedure code(s).): The procedure code is missing, incomplete, or invalid.
  • N56 (Procedure code billed is not correct/valid for the services billed or the date of service billed.): The procedure code isn't correct for the services or date billed.
  • CO-181 (Procedure code was invalid on the date of service.): The procedure code wasn't valid on the date of service.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): A broader missing or invalid information denial.
  • CO-182 (Procedure modifier was invalid on the date of service.): The modifier wasn't valid on the date of service.

CO-199 FAQ

Does CO-199 apply to professional claims?

No. Revenue codes are used on institutional claims (UB-04 or 837I) by hospitals, SNFs, home health agencies, and other facilities. Professional CMS-1500 claims don't have revenue codes.

Where do revenue and procedure code pairings come from?

From payer edits such as Medicare's outpatient code editor and the payer's own billing guidelines, which specify which HCPCS codes may be reported with which revenue codes.

How do I fix CO-199?

Correct the revenue code or HCPCS code on the line and submit a corrected claim with the appropriate type of bill frequency code, usually 7 for a replacement. Then fix the chargemaster entry.

Can one chargemaster error cause many CO-199 denials?

Yes. Because the chargemaster feeds every claim, one wrong revenue code mapping can deny the same service on every patient. Fixing the source entry stops new denials, but past claims still need correcting one by one.