Point of taxation: invoice issuance or earlier payment determines tax point; completion date applies if invoice delayed. The point of taxation is the time the invoice is issued, or if the invoice is not issued within the specified period, the date of completion of the service; payments received before invoice issuance determine the point of taxation to the extent of those payments. Advances trigger point of taxation on receipt. For continuous supplies specified by contract, the date of completion of each contractual event is treated as the date of provision. Providers may, within a small excess-payment threshold, elect to apply the invoice-based point of taxation to the excess.