The formula for calculating GST and QST used in 2016
The calculation of the GST and the QST is normally done in two steps, you must calculate the GST (at 5%) on the sale price, then add the QST (at the rate of 9.975%) at the same price of the sale. The calculation of the GST and QST can also be done in one step, you must use the rate of 14.975% to calculate both taxes. The resulting amount includes GST and QST.