CO-163Contractual ObligationDocumentation
CO-163 Denial Code: Referenced attachment not received
The claim said documentation was coming (PWK segment/attachment indicator) but the payer never got it.
Why CO-163 happens
- ●Attachment control number mismatch between claim and submission
- ●Fax/upload failed or went to the wrong payer channel
How to fix a CO-163 denial
- 1
Resubmit the attachment through the payer's documented channel referencing the claim/PWK number
- 2
Confirm receipt before the payer's deadline lapses into CO-226/227
How to prevent it
Use trackable electronic attachment channels (275 transactions or portal uploads) over fax.
Drowning in CO-163 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.