Time of supply of goods determines tax liability on earlier of invoice issuance or payment receipt, including reverse charge. Time of supply of goods is the earlier of invoice issuance (or required issuance) and receipt of payment, with supply deemed only to the extent covered by the invoice or payment and payment date taken as earlier of book entry or bank credit. For reverse charge, time of supply is earliest of goods receipt, recipient payment entry or bank debit, or the date following thirty days after supplier invoice; fallback to recipient books entry applies. Voucher supplies are timed at issue if identifiable or at redemption. If none apply, timing follows the periodic return date or tax payment; additions for interest or penalties are timed on receipt.