CO-B4Contractual ObligationTimely Filing
CO-B4 Denial Code: Late filing penalty
A penalty reduction for late filing — the claim paid, but reduced because it arrived late (distinct from CO-29's outright denial).
Why CO-B4 happens
- ●Claim filed inside a grace window that pays with a penalty
How to fix a CO-B4 denial
- 1
Verify the penalty percentage; appeal with proof of timely filing if you have it
How to prevent it
Same fix as CO-29 — charges out the door within 48–72 hours.
Drowning in CO-B4 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.