Point of taxation: invoice issuance or receipt of payment determines tax point for continuous supply of services under the rules. The point of taxation for continuous supply of services is the invoice date for services provided or to be provided, or if no invoice is issued within fourteen days of completion, the completion date; where payment is received before the invoice date, the date of receipt of payment is the point of taxation to the extent of that payment. Periodic contractual events are treated as completion dates for taxation, and any advance received is taxable on its receipt.