CO-164Contractual ObligationDocumentation
CO-164 Denial Code: Attachment not received timely
The referenced documentation arrived after the payer's deadline — the claim adjudicated without it.
Why CO-164 happens
- ●Documentation sent late relative to the payer's attachment window
How to fix a CO-164 denial
- 1
Submit the documentation with an appeal/reopening request explaining the timeline
How to prevent it
Send attachments the same day as claims that reference them.
Drowning in CO-164 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.