CO-20CO group · Coordination of benefits

CO-20 denial code: this injury is covered by a liability carrier

CO-20 sends the claim to a liability insurer that may not exist, and the health plan's obligation while that is unresolved is the point worth arguing.

CO-20 fires when the payer concludes an injury falls under a liability policy — a motor accident, a premises claim — and directs the claim there. It is a coordination decision, and it is frequently made from a diagnosis code rather than from any evidence a liability claim exists.

What CO-20 means

An injury diagnosis will trigger this edit at many payers automatically. If there is no liability carrier, no claim and no settlement, the health plan remains the payer of record, and saying so in writing is usually what resolves it. Where a liability claim does exist, the health plan may still be required to pay and seek recovery afterwards rather than leaving the provider unpaid while litigation runs.

Why CO-20 fires

  • An injury diagnosis triggered an automatic coordination edit.
  • The patient reported an accident at registration and it was coded onto the claim.
  • A liability claim exists and the payer is deferring to it.
  • A prior accident-related claim set a flag on the member record.

Is CO-20 worth appealing?

Sometimes worth appealing

State the facts. Where no liability carrier or claim exists, say so in writing and ask the plan to adjudicate; where one does, ask what the plan's own document says about paying and pursuing recovery.

How to resolve or appeal CO-20

  1. 1

    Establish whether a liability claim exists

    From the patient, in writing where possible — the payer is often working from an assumption.

  2. 2

    Ask the plan to adjudicate pending recovery

    Many plan documents provide for paying and then subrogating rather than deferring indefinitely.

CO-20 — frequently asked

Why did this fire with no accident?
Injury diagnosis codes trigger it automatically at many payers. The edit is not evidence that a liability carrier exists.
Does the patient have to sign anything?
Payers commonly request an accident questionnaire, and an unreturned one keeps the claim suspended. Getting it completed is often the whole resolution.

Related guides

CO-21 · Coordination of benefitsCO-19 · Coordination of benefitsCO-22 · Coordination of benefits

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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