CO-164: Attachment/Documentation Not Received Timely

What Does CO-164 Mean?

CO-164 is the primary pairing for this code. The payer is treating the late documentation as a contractual issue — the provider's obligation to submit supporting materials within the specified deadline was not met, and the claim is denied as a result. Under CO, this is a provider write-off and you cannot bill the patient. Your primary recourse is to submit the documentation immediately with an explanation and, if rejected, appeal with evidence of extenuating circumstances or proof of prior timely submission attempts.

When CARC 164 appears on a remittance, the payer is telling you that the required supporting documentation referenced on the claim — medical records, operative notes, test results, authorization letters, or other attachments — was not received within the payer's specified time limit. The payer may have eventually received the documents, but they arrived after the window for acceptance had closed.

CARC 164 is distinct from CARC 163, which indicates documentation was never received at all. With CARC 164, the payer is specifically flagging a deadline violation. Most payers set documentation submission deadlines ranging from 30 to 90 days from the date of the initial request or claim submission. Some payers enforce these deadlines strictly, while others may allow exceptions for demonstrated good cause.

The root causes are typically operational: internal workflow bottlenecks that delayed the gathering of records, unawareness of the specific payer's deadline, failed or delayed electronic or fax transmissions, or documentation requests that were missed entirely and discovered only after the deadline passed. In many practices, CARC 164 denials are preventable with better tracking systems and internal deadline management. The financial impact is significant because these denials often represent fully approvable claims that simply missed an administrative deadline.

Common Causes

How to Resolve

Submit the documentation immediately, explain the delay, and appeal if extenuating circumstances prevented timely delivery.

1. Verify the deadline and submission timeline Confirm the payer's documentation deadline and compare against your records of when materials were sent. Determine if you are within any grace period.
2. Submit documentation with explanation Send the required materials immediately with a cover letter explaining the delay. Reference the claim number and include all required attachments.
3. Appeal with evidence if rejected If the payer does not accept the late documentation, file a formal appeal citing extenuating circumstances and including any proof of prior submission attempts.
4. Request a deadline exception Contact the payer's provider relations team to request a formal exception to the documentation deadline based on documented good cause.

Common RARC Pairings

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

How to Prevent CO-164

• Track all documentation requests in a centralized system with automated reminders 2-3 weeks before each payer's deadline
• Establish internal deadlines that are well ahead of the payer's actual deadline to provide a buffer
• Assign a dedicated team or staff member to handle documentation request responses promptly
• Use electronic submission methods with delivery confirmation to minimize transmission delays
• Conduct weekly reviews of pending documentation requests to identify items approaching deadlines
• Maintain a reference guide of each payer's specific documentation submission timeframes

General Prevention

• Maintain a centralized tracking system for all documentation requests with deadlines and automatic reminders well before the due date
• Establish internal deadlines that are 2-3 weeks ahead of the payer's actual deadline to provide a buffer for gathering and reviewing materials
• Implement an automated alert system that flags claims with pending documentation requests and escalates as deadlines approach
• Train staff on payer-specific documentation submission timeframes and ensure the information is readily accessible
• Use electronic submission methods with delivery confirmation to minimize transmission delays and create a verifiable record
• Assign dedicated staff or a documentation response team to handle documentation requests promptly when they arrive
• Conduct regular reviews of pending documentation requests to identify items at risk of missing deadlines

Also Filed As

The same CARC 164 may appear with different Group Codes:

Related Denial Codes