Quick Explanation
Denial code CO-163 indicates that the payer processed a claim containing an electronic indicator for incoming supporting documentation, but the referenced attachment was never received or successfully matched to the claim. This typically pauses the adjudication process because the clinical evidence required to prove medical necessity is missing.
Common Causes for CO-163
Denials with code CO-163 typically happen for the following specific reasons:
- The electronic claim contained a populated PWK (Paperwork) segment, but the actual document was not sent via fax, mail, or portal.
- The attachment was submitted without the required payer cover sheet or matching patient identifiers, preventing the system from linking it to the claim.
- The medical documentation was sent after the payer's allowed timeframe for receiving supplementary records had expired.
- The Attachment Control Number (ACN) transmitted on the EDI claim did not match the identifier on the physical or digital document sent.
How to Prevent CO-163 Denials
To avoid receiving this denial in the future, implement these specific checks:
- Establish a standard operating procedure to upload attachments directly through the payer's secure provider portal at the time of claim submission.
- Ensure every paper-submitted or faxed attachment utilizes the payer's specific barcoded cover sheet with matching patient and claim details.
- Verify that the Attachment Control Number (ACN) in the electronic PWK segment matches the physical document header exactly.
- Regularly audit clearinghouse reports to verify successful receipt and acknowledgement of claims requiring attachments.
Appeal Letter Template for CO-163
If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.
[Your Practice Header]
[Date]
[Payer Name]
[Appeals Department Address]
RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: CO-163 - Attachment referenced on the claim was not received
Dear Appeals Department,
I am writing to appeal the denial of the above-referenced claim, which was denied with code CO-163: "Attachment referenced on the claim was not received".
We are appealing the denial under code CO-163 for the enclosed claim. In accordance with CMS guidelines and standard electronic data interchange (EDI) companion guidelines regarding the submission of supplemental documentation, we are hereby submitting the requested medical records directly with this appeal letter. The attached documentation contains all necessary clinical information, including the corresponding Claim ID, patient details, and date of service, to substantiate the medical necessity of the billed services. We request that you immediately associate these clinical records with the claim and reprocess it for complete reimbursement.
Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].
We respectfully request that you reprocess this claim for payment.
Sincerely,
[Your Name]
[Title]
[Practice Name]
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