CO-105Contractual ObligationPayment Adjustment
CO-105 Denial Code: Tax withholding
Tax withheld from the payment — e.g., backup withholding when the payer lacks a valid W-9/TIN match.
Why CO-105 happens
- ●TIN/name mismatch with IRS records triggering backup withholding
- ●State-level tax withholding requirements
How to fix a CO-105 denial
- 1
Submit a corrected W-9 to the payer immediately — withholding continues until fixed
- 2
Recover withheld amounts through your tax filing
How to prevent it
Verify TIN/legal-name consistency across all payer enrollments.
Drowning in CO-105 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.