The property of the Union shall, save in so far as Parliament may by law otherwise provide, be exempted from all taxes imposed by or under any law made by the Legislative Assembly or by or under any other law in force in the Capital:
     Provided that nothing in this section shall, until Parliament by law otherwise provides, prevent any authority within the Capital from levying any tax on any property of the Union to which such property was immediately before the commencement of the Constitution liable or treated as liable, so long as that tax continues to be levied in the Capital.