Tax invoice obligations: registered suppliers must issue tax invoices at or before supply with prescribed particulars and exceptions. Registered suppliers of taxable goods must issue a tax invoice before or at removal or delivery showing description, quantity, value and tax; suppliers of taxable services must issue a tax invoice within a prescribed period before or after provision, subject to notified exceptions. The law allows revised invoices after registration, bills of supply for exempt or composition supplies below a low-value threshold, receipt and refund vouchers for advance payments, and special invoicing timing for continuous supplies and events tied to payment.