N4N-series (general use)COB & Secondary
N4: Missing prior insurer EOB
The claim needs the prior/primary carrier's explanation of benefits and it wasn't included.
Commonly appears with these denial codes
The denial code gives the category; N4 pinpoints the specific problem. Read them together before touching the claim.
What to do about it
Attach the primary EOB (or transmit COB data electronically) and resubmit to the secondary payer.
OakClaim fixes root causes, not just claims.
Free billing audit shows which remark codes keep recurring in your AR — and what they're costing you.