Time of supply rules for tax rate changes set the supply date by invoice and payment sequencing. Change in rate of tax determines the time of supply by reference to invoice issuance and payment timing. For supplies before a rate change, the earlier of invoice date or payment receipt generally fixes the time of supply, with invoice date prevailing when issued prior to the change and payment follows, and payment date prevailing when received prior and invoice follows. For supplies after the change, payment receipt or invoice date similarly governs depending on their sequence. 'Date of receipt of payment' is the earlier of books entry or bank credit, except where bank credit occurs more than four working days after the rate change.