Unless otherwise provided for in these Supplementary Provisions, the provisions of the Income Tax Act as amended by the provisions of Article 1 (referred to as the "New Income Tax Act" in Article 8 of the Supplementary Provisions) apply to income tax for the year that includes the date on which this Act comes into effect (hereinafter referred to as "the effective date") and subsequent years, and the provisions then in force continue to govern income tax for years before the year that includes the effective date.