How does the review window work for big projects (Tier 4)?

Tier 4 jobs (£15,000–£50,000) are paid in three milestones — 30% at start, 40% at midpoint, 30% at completion. Each milestone has its own 72-hour review window once the tradesperson uploads timestamped photo evidence of the milestone work. You can approve or raise a dispute within those 72 hours. If you do neither, the milestone payment releases automatically.