Section 21

When by virtue of an order made under subsection 11(1) a customs duty is fixed on any goods which previously were not dutiable goods or any customs duty on goods is abolished or when the importation or exportation of any goods is prohibited or any such prohibition is abolished by an order made under section 31 and it becomes necessary for the purpose of this Act to determine the time at which an importation or exportation of any goods made and completed shall be deemed to have had effect, such importation or exportation shall, notwithstanding anything in this Act contained, be deemed to be the time at which the goods are released by the proper officer of customs.