OA-20: Liability Carrier Responsible

What Does OA-20 Mean?

OA-20 appears in coordination of benefits scenarios where the payer flags the claim as liability-related but the financial disposition is not yet determined. This may occur when the liability carrier's involvement is unclear, when multiple payers are involved, or when the payer needs additional information before assigning financial responsibility. The OA designation indicates an administrative adjustment pending further investigation.

When CARC 20 shows up on a remittance, the health insurer is declining payment because the injury or illness is linked to a liability claim. This typically involves automobile accidents, slip-and-fall incidents, dog bites, product liability injuries, or any situation where a third party's insurance — not the patient's health plan — bears financial responsibility for the medical expenses. The health insurer is saying: someone else's insurance should pay for this.

The denial is triggered when the payer's system detects indicators of a liability-covered event, often through diagnosis codes associated with injuries (motor vehicle accident codes, external cause codes), the patient's own disclosure on intake forms, or information from other payers in the coordination of benefits chain. Unlike workers' compensation denials (CARC 19), CARC 20 specifically points to liability insurance — the type of coverage that pays when one party is legally liable for another's injuries.

Redirecting these claims requires a different workflow than standard health insurance billing. Liability carriers operate on fundamentally different timelines — personal injury claims can take months or years to settle — and they may require pre-authorization, attorney liens, or letters of protection before paying medical bills. Providers who regularly treat accident and injury patients need established processes for identifying liability coverage at intake and managing the extended billing cycle these claims typically involve. If the liability carrier's coverage is exhausted, you can then submit to the patient's health insurance with documentation of the exhausted benefits.

How to Resolve

Confirm the injury involves a liability carrier, obtain their claim information, and redirect the claim to the correct payer — or dispute the classification if it was applied in error.

1. Review the ERA for COB indicators Check for accompanying RARCs that explain the OA designation. Determine if additional payer information is needed or if a specific liability carrier has been identified.
2. Investigate the liability situation Contact the patient to clarify the injury circumstances and determine whether a liability carrier exists. If so, obtain their information and submit the claim accordingly.
3. Redirect or dispute based on findings Route the claim to the correct payer based on your investigation, whether that is a liability carrier, the health insurer (with supporting documentation), or a secondary payer in the COB chain.

How to Prevent OA-20

• Collect comprehensive information about injury circumstances and all potentially involved payers during registration
• Verify COB order for all injury-related visits before initial claim submission
• Maintain detailed records of patient-reported injury details to support correct payer identification

Also Filed As

The same CARC 20 may appear with different Group Codes:

Related Denial Codes