(a)If any amount of tax, interest, penalty, or any other amount due under this Act or the Acts repealed by Section 52 of Act No. 2 of 1959 or the Act repealed by Section 81 of Act No. 5 of 1995 or the Act repealed by this Act (hereinafter referred to as the repealed Act) remains unpaid on the expiry of the period prescribed for the payment thereof by or under this Act or the repealed Act or on the expiry of the period specified in any notice of demand or order issued or made under this Act or the repealed Act or the rules made thereunder, for the payment thereof, the dealer or person liable to pay such amount shall be deemed to be in default as to the whole of the amount then outstanding.