Key Scenarios
✅ Old Rate (5%)
Supply completed AND invoiced before 1 Jan 2022. Prepayment received AND invoiced before rate change. Contract signed before announcement AND supply completed within transitional window.
❌ New Rate (10%)
Supply completed after 1 Jan 2022 regardless of contract date. Invoice issued after rate change for supply straddling the change. New contracts signed after announcement. Recurring supplies after rate change date.
⚠️ Complex Cases
Continuous supply straddling the change date — apportion between old and new rate. Milestone payments spanning the change. Deposits received at old rate but supply at new rate — credit note and re-invoice. Retainer agreements — new rate from change date.