OA-163: Attachment/Documentation Not Received

What Does OA-163 Mean?

OA-163 is uncommon and typically appears when the missing documentation involves coordination between multiple parties — for example, when the secondary payer is waiting for documentation from the primary payer's adjudication. The OA group code indicates the issue is not a standard contractual obligation but rather an administrative gap that needs to be resolved between the involved parties.

When CARC 163 appears on a remittance, the payer is telling you that the claim referenced supporting documentation — such as medical records, operative notes, test results, or pre-authorization letters — but that documentation never arrived. The payer cannot adjudicate the claim without the referenced materials, so it is denied pending receipt of the missing attachments.

This is one of the more frustrating denials because the clinical service was likely appropriate and properly coded. The issue is purely logistical: either the documentation was never sent, it was sent but failed to transmit (common with fax and electronic attachment systems), or it was sent but could not be matched to the claim because of a reference number mismatch. In some cases, the payer received the documents but classified them as incomplete or illegible, which has the same effect as not receiving them.

CARC 163 is almost always paired with Group Code CO, making it a contractual adjustment that the provider must resolve. The fix is straightforward: gather the required documentation, verify it meets the payer's format and submission requirements, and resubmit. The critical detail is ensuring the attachment control number or claim reference links the documents to the correct claim. Without that link, the payer's system may receive the documents but fail to associate them with the pending claim, resulting in a repeat denial.

How to Resolve

Identify the missing documentation, verify submission requirements, and resubmit the claim with all referenced attachments properly linked.

1. Identify the coordination issue Determine whether the missing documentation relates to primary payer adjudication details, coordination of benefits information, or other cross-payer requirements.
2. Facilitate documentation exchange Obtain the required documentation from the primary payer or other party and submit it to the denying payer with the claim reference.
3. Request reprocessing Once the documentation is submitted, request the payer reprocess the claim and confirm receipt of the materials.

How to Prevent OA-163

• Ensure primary payer EOBs and adjudication details are available before submitting secondary claims
• Maintain organized records of all payer communications and adjudication documents
• Track coordination of benefits documentation requirements for each payer

Also Filed As

The same CARC 163 may appear with different Group Codes:

Related Denial Codes