CARC 20 Active

CO-20: Liability Carrier Responsible

TL;DR

Provider responsibility — correct and resubmit to the appropriate payer. The patient is not liable for this amount.

Action
Resubmit
Who Pays
Provider
Appeal
Yes
Patient Impact
None
Disclaimer
This content is for informational purposes only and does not constitute professional billing advice. Always verify information against your payer contracts and current coding guidelines. Consult a certified billing specialist for specific claim issues.

What Does CO-20 Mean?

With CO (Contractual Obligation), the CARC 20 adjustment for liability carrier responsible indicates the claim needs to be corrected or routed to a different payer. The patient is not liable for this amount. Correct the issue and resubmit.

CARC 20 indicates liability carrier responsible. The payer determined that the service or a portion of it does not meet coverage criteria under the patient's current plan benefits or the applicable coverage rules.

Common scenarios that trigger this adjustment include: services for an injury from an automobile accident were billed to health insurance instead of the auto liability carrier; Payer determined that a third-party liability carrier (auto, premises) is responsible for the injury; Health plan is pursuing subrogation and denying the claim pending liability determination. The group code paired with CARC 20 determines who bears the financial responsibility — CO places it on the provider as a contractual obligation, OA indicates a coordination of benefits or other payer adjustment, PR shifts it to the patient.

Common Causes

Cause Frequency
Auto accident claim billed to health plan Services for an injury from an automobile accident were billed to health insurance instead of the auto liability carrier Most Common
Third-party liability identified Payer determined that a third-party liability carrier (auto, premises) is responsible for the injury Common
Subrogation in progress Health plan is pursuing subrogation and denying the claim pending liability determination Occasional

How to Resolve

  1. Review the denial reason Examine the CO-20 adjustment and any RARC codes to identify what needs to be corrected.
  2. Correct the claim Address the issue that triggered the denial — update the claim with correct information or route to the appropriate payer.
  3. Resubmit the claim Submit the corrected claim per the payer's guidelines.
Appeal Guide

If no liability carrier is involved, appeal with documentation including patient statement, police report (if available), and medical records showing the condition is not a liability case. If liability applies, submit to the liability carrier instead.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-20:

RARC Description
N36 Claim must meet primary payer requirements Submit to liability carrier first →
N479 Missing/incomplete/invalid condition information Provide accident details if appealing →

How to Prevent CO-20

Also Filed As

The same CARC 20 may appear with different Group Codes:

OA-20 PR-20

Related Denial Codes

CO-19 — Workers' Compensation Claim CO-21 — No-Fault Carrier Responsible CO-22 — Coordination of Benefits - Another Payer May Cover CO-276 — Prior Payer Denied Services Not Covered by This Payer CO-226 — Provider Information Not Provided or Insufficient

Sources

  1. https://x12.org/codes/claim-adjustment-reason-codes
  2. https://revenuecyclemgmt.com/claim-adjustment-reason-codes/
  3. https://www.rivethealth.com/blog/carcs-rarcs-claim-adjustment-remittance-advice-codes
  4. Codes maintained by X12. Visit x12.org for official definitions.