30 March 2017
Last date of filing ITR for A.Y 2016-17 is 31/03/2018.
Returns which are filed on or before due date (i.e Original return) are filed under 139(1) (for A.Y 2015-16 due date of filing return as per 139(1) is 30/09/2016) therefore return is to be filed under section 139(4) (i.e belated return).