OA-B20: Service Furnished by Another Provider

What Does OA-B20 Mean?

OA-B20 indicates the service attribution issue involves coordination of benefits where the financial responsibility is not clearly assigned. This occurs when multiple payers are involved and the service was partially furnished by a provider covered under a different payer.

CARC B20 fires when the payer's records indicate that the billed procedure or service was already provided — in whole or in part — by a different healthcare provider. The payer is protecting against double payment for the same service. This code is fundamentally about provider attribution: who actually performed the service, and is there a legitimate claim from each party involved?

The most common trigger is a billing coordination failure between collaborating providers. When a primary care physician refers a patient to a specialist who performs a procedure, both providers may inadvertently bill for the same service or components of it. Similarly, when a practice outsources laboratory work, imaging, or technical components to an external facility, both the referring practice and the performing facility may submit claims. B20 catches these overlaps and denies the claim from the provider the payer considers duplicative.

B20 pairs primarily with CO, making the denied amount a provider write-off. If the other provider legitimately performed the service, the denial is correct — you cannot bill for work someone else did. However, if the services were shared (co-surgery, team surgery, or split technical/professional components), the denial may be incorrect and should be resolved by adding appropriate modifiers. Modifier 62 for two-surgeon scenarios, modifiers 80-82 for assistant surgeon roles, and TC/26 modifiers for technical/professional component splits all help the payer distinguish legitimate shared billing from duplicate claims.

Common Causes

How to Resolve

Determine whether the service was genuinely furnished by another provider, coordinate billing with the other provider, and resubmit with appropriate modifiers if the service was shared or independently performed.

1. Map the provider and payer relationships Identify which provider billed which payer for which component of the service.
2. Resubmit with COB documentation Include documentation of the other provider's claim and payment when resubmitting to clarify the service attribution.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-B20:

How to Prevent OA-B20

• Coordinate billing across all providers and payers involved in shared services
• Include cross-payer remittance information when submitting claims for services that involve multiple providers

General Prevention

• Coordinate billing with referring providers and specialists before submitting claims for shared or outsourced services
• Implement clear billing protocols that define which provider bills when services are performed collaboratively
• Use appropriate modifiers (62, 66, or 80-82) to indicate shared surgical or assistant services
• Verify with the payer whether the service requires a specific designated provider before rendering and billing
• Document clearly in the medical record which provider performed each component of a service

Also Filed As

The same CARC B20 may appear with different Group Codes:

Related Denial Codes