The taxpayer (PCS), which produced and sold potash from mines in Saskatchewan, was subject to both a profit tax and to the making of “base payments” under the Mineral Taxation Act, 1983 (Saskatchewan), which was computed by applying a tax rate of tax determined in accordance with the PPTS multiplied by the number of tonnes of potash sold or otherwise disposed of, minus certain permitted deductions. Since the base payment was calculated based on the quantity of potash that was sold, it was only incurred by PCS as a result of sales of potash by it.