Section 346(2) in The Delhi Municipal Corporation Act, 1957
(2)No person shall occupy or permit to be occupied any such building or use or permit to be used any building or a part thereof effected by any such work until permission has been granted by the Commissioner in this behalf in accordance with bye-laws made under this Act:Provided that if the Commissioner fails within a period of thirty days after the receipt of the notice of completion to communicate his refusal to grant such permission, such permission shall be deemed to have been granted.