Unless otherwise provided, the provisions of Chapter III of the New Act apply to corporation tax for business years of a corporation (including an association or foundation without juridical personality prescribed in Article 2, item (viii) of the Corporation Tax Act (Act No. 34 of 1965); the same applies hereinafter) beginning on or after the Effective Date, and with regard to corporation tax for business years of a corporation that began before the Effective Date, the provisions then in force continue to govern.