CO-19CO group · Coordination of benefits

CO-19 denial code: this is a work-related injury, liability of the workers' comp carrier

CO-19 is a liability-routing denial: the health plan says workers' comp owns this. It's an appeal only when the injury wasn't actually work-related.

CO-19 means the payer believes the condition is a work-related injury or illness, making the workers' compensation carrier responsible rather than the health plan. Usually the claim belongs with workers' comp. It becomes a health-plan appeal when the injury was not work-related and the payer flagged it in error.

What CO-19 means

Health plans exclude conditions covered by workers' compensation. When a diagnosis or claim history suggests a workplace injury, the health plan denies as CO-19 and points to the comp carrier as the liable party.

Why CO-19 fires

  • The injury genuinely arose from or in the course of employment.
  • A diagnosis or external-cause code suggested a workplace injury.
  • An open workers' comp claim exists for the patient.
  • The condition was flagged as work-related in error and is actually a covered health-plan benefit.

Is CO-19 worth appealing?

Rarely an appeal — usually a fix

If the injury is work-related, bill the workers' compensation carrier — the health plan's denial is correct. Appeal the health plan only when the condition was not work-related: provide the clinical history and, where available, a denial or determination from the comp carrier showing it declined responsibility.

How to resolve or appeal CO-19

  1. 1

    Determine the liable payer

    If the injury is work-related, submit to the workers' compensation carrier rather than appealing the health plan.

  2. 2

    Document a non-work-related cause

    When the condition is not work-related, appeal with the clinical history establishing the cause and correcting any external-cause coding.

  3. 3

    Attach the comp carrier's position

    A workers' comp denial or determination that the injury isn't compensable is strong support for the health plan to assume responsibility.

CO-19 — frequently asked

Should CO-19 go to workers' comp?
If the injury is work-related, yes — bill the comp carrier. Appeal the health plan only when the condition wasn't work-related and was flagged in error.
What if both deny?
When workers' comp denies as non-compensable, use that determination to appeal the health plan to assume responsibility for the covered service.

Related guides

CO-22 · Coordination of benefitsCO-24 · Coordination of benefitsCO-109 · Eligibility

Sources

Reason-code meanings are paraphrased from the X12 Claim Adjustment Reason Code list for plain-language reference; they are not reproduced verbatim. This is general information, not legal, coding, or medical advice — always confirm against the payer's remittance and policy.

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