choose the instalment option) will pay GST at 12.5%. Periodic supplies: On 1 July 2010 Matt signs an agreement to lease a car park from Parking Co. The agreement requires Matt to pay a fee of $120 each month (inclusive of GST), payable on 20th of each month. A tax invoice was provided to Matt at the time he signed the agreement. The tax invoice requires Matt to pay a fee of $120 per month (inclusive of GST), payable on the 20th of each month. Each monthly payment is a separate supply. The time of supply is the time each payment becomes due or is received, which ever is the earlier. Here, that would be the 20th of each month. The GST Act also allows a supplier to increase their price to provide for the increase in the rate of GST. In Matt's case Parking Co may increase the monthly payments to $122.66 to reflect the increase in the GST rate. Similar outcomes would apply to commercial leases and other similar commercial arrangements. For example, a monthly fee for the use of an electronic database, or a gym membership. A plumber has asked what rate of GST should be charged on invoices issued prior to 1 October 2010, but for which payment will not be received until after 1 October. All invoices issued prior to 1 October 2010 should have GST included at 12.5% - even if you do not expect to be paid until after that date. If you