Point of taxation timing adjusted when tax rate changes; invoice and payment dates determine the taxable point. Point of taxation when there is a change in effective rate of tax is set by the sequence of service provision, invoice issuance and payment: for services before the change the earlier of payment or invoice generally determines tax point, with specific rules when one of those events falls before and the other after the change; for services after the change analogous rules apply, assigning tax point to invoice date or payment date according to their timing relative to the rate change. Textual substitutions to the phrase and omission of an explanatory clause are recorded.