OA-173: Service/Equipment Not Prescribed by Physician

What Does OA-173 Mean?

OA-173 is uncommon and typically appears in coordination of benefits situations where the missing prescription affects how the claim is adjudicated across multiple payers. The primary payer flags the missing order under OA, signaling that the issue must be resolved before any payer can process the claim.

When CARC 173 appears on a remittance, the payer is telling you that the service or piece of equipment you billed was not backed by a physician prescription or order. Payers require a valid physician order as a prerequisite for reimbursement on many service types — particularly durable medical equipment, home health services, clinical lab tests, and certain therapies. Without that documented order, the payer treats the service as unauthorized and denies the claim.

This code almost always appears with Group Code CO, placing the financial burden on the provider. The denial signals a documentation compliance failure: either the physician order was never obtained, it was incomplete, or it was not included with the claim submission. In some cases, the order exists in the patient's medical record but was not properly communicated to the billing department or was not attached to the claim.

Co-173 is distinct from CARC 174 (service not prescribed prior to delivery), which focuses on timing. CARC 173 is broader — the payer found no prescription at all, regardless of timing. Resolution typically involves locating or obtaining the physician order and resubmitting, though if the service was truly delivered without a prescription, the provider may need to absorb the cost.

How to Resolve

Locate or obtain the missing physician prescription, then resubmit the claim with complete documentation.

1. Resolve the prescription issue first Before addressing the COB aspect, obtain the missing physician order and submit it to the primary payer for reprocessing.
2. Reprocess with primary payer Once the primary payer adjudicates the claim correctly with the prescription on file, use the updated ERA to submit to the secondary payer.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-173:

How to Prevent OA-173

• Ensure physician orders are obtained and documented before claims are submitted to any payer in the billing sequence
• Include prescription verification as part of the pre-claim submission checklist regardless of which payer is being billed

General Prevention

• Ensure all services and equipment have a valid, signed physician prescription or order on file before delivery
• Implement pre-authorization workflows that verify prescription requirements are met before rendering services
• Train staff on documentation requirements including what constitutes a complete prescription for each service type
• Use electronic health record systems with required-field prompts to prevent incomplete orders from proceeding
• Conduct regular audits of prescription documentation to identify and correct gaps before claim submission
• Stay current on payer-specific policies regarding which providers are authorized to prescribe specific services or equipment
• Establish communication protocols between clinical and billing departments to flag orders that lack required documentation

Also Filed As

The same CARC 173 may appear with different Group Codes:

Related Denial Codes