CO-164: Attachment/Documentation Not Received in Timely Fashion

What Does CO-164 Mean?

With CO (Contractual Obligation), the CARC 164 denial for attachment/documentation not received in timely fashion is the provider's contractual responsibility. The patient is not liable for this amount. However, the provider may appeal with supporting clinical or administrative documentation if the denial is believed to be in error.

CARC 164 indicates attachment/documentation not received in timely fashion. The payer rejected the claim because it was not received within the required filing deadline specified by the payer's guidelines or the provider contract.

Common scenarios that trigger this adjustment include: the required supporting documentation was submitted after the payer's specified timeframe for receiving attachments, resulting in the claim being denied; The payer requested additional documentation (ADR) and the provider did not respond within the required timeframe; The attachment was mailed or faxed separately from the claim and arrived after the payer's processing deadline. The group code paired with CARC 164 determines who bears the financial responsibility — CO places it on the provider as a contractual obligation, OA indicates a coordination of benefits or other payer adjustment, PR shifts it to the patient.

Common Causes

How to Resolve

1. Review the denial Examine the CO-164 denial and any RARC codes to understand the specific basis for the coverage determination.
2. Gather supporting documentation Collect medical records, clinical notes, authorization documents, or other evidence that supports the medical necessity or coverage of the denied service.
3. File the appeal Appeal with proof that the documentation was submitted within the payer's deadline (fax confirmations, electronic receipts, mail tracking). If the submission was late, include an explanation of extenuating circumstances and the complete documentation.
4. Track the appeal outcome Monitor the appeal status and follow up as needed. If denied again, consider further levels of appeal if available.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-164:

How to Prevent CO-164

• Know each payer's documentation submission deadlines and track them systematically
• Respond to additional documentation requests (ADRs) immediately upon receipt
• Submit attachments simultaneously with claims whenever possible rather than sending separately
• Use electronic submission methods for faster delivery and confirmation tracking
• Implement workflow alerts to track pending documentation requests and their deadlines
• Maintain organized records to quickly compile and submit documentation when requested

Also Filed As

The same CARC 164 may appear with different Group Codes:

Related Denial Codes