Time of supply of goods determines tax liability, based on earlier of invoicing or payment, with tailored reverse charge and voucher rules. The time of supply for goods is the earlier of invoice issuance (or last required invoice date) and receipt of payment, with payment deemed at earlier of book entry or bank credit. For reverse charge supplies the earliest of goods receipt, recipient's payment entry or bank debit, or a date after a prescribed period following invoice governs; if indeterminate, the recipient's books fix the time. Vouchers are supplied on issue if identifiable, otherwise on redemption. If none apply, the time is the return filing date or the date tax is paid. Value additions (interest, late fee, penalty) are taxable when received by the supplier.