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 the start, 40% at the midpoint, and 30% on completion. Each milestone opens its own 72-hour review window once the tradesperson has provided photo evidence that the stage is complete. You can approve or raise a dispute within those 72 hours; if you do neither, that milestone payment releases automatically.