Time of supply rules tie tax point to invoice or payment timing when tax rates change, clarifying bank credit treatment. Change in tax rate shifts the time of supply to the earlier of invoice date or payment date depending on their sequence relative to the rate change: if both invoice and payment occur after the change the earlier governs; if invoice predates but payment postdates the change the invoice date governs; if payment predates but invoice postdates the change the payment date governs; corresponding provisions apply when supply occurs after the change. The bank credit timing proviso and the explanation that receipt means the earlier of book entry or bank credit are operative.