CO 199 denial code

Claim adjustment reason code 199. Often reported as CO 199.

Revenue code and procedure code mismatch

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 199 means

On an institutional claim, the revenue code on the line does not fit the CPT or HCPCS code billed with it.

Facility claims pair a revenue code with a procedure code on each line. The payer has rules about which pairs make sense, and this line failed that check.

The fix is usually a coding or chargemaster correction rather than a coverage problem, so the claim can often be corrected and resubmitted.

Group codes seen with 199

On a remittance, 199 comes after a group code. These are the ones it is most often reported with:

• CO 199 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• The chargemaster maps the procedure to a revenue code the payer does not accept for it.
• A drug, supply or lab code was billed under a general revenue code that needs to be more specific.
• A procedure code was updated but the linked revenue code was not.

What to do next

1. Check the payer's revenue code and HCPCS pairing guidance for the billed line.
2. Correct the revenue code or procedure code on the claim and resubmit as a corrected claim.
3. Ask the chargemaster team to fix the mapping so later claims go out clean.

Related codes

• 282 (reason code) Code does not fit the type of bill
• 16 (reason code) Missing information or billing error