Timely filing denials rarely begin at the billing desk. By the time a claim misses its filing deadline, the real problem may have started much earlier—with delayed documentation, coding backlogs, unbilled charges, or a rejection that left too little time for correction. This article explores how seemingly small upstream delays can quietly erode the filing window and why treating timely filing as an end-to-end revenue cycle metric can help organizations identify risk before it becomes a denial.