24 March 2015
Last date of filing belated return u/s 139 (4) for AY 2012-13 was 31.03.2014.
Only way to file return of AY 2012-13, is to invoke section 119(2)(b) i.e., application for condonation of delay. See below link for details--- http://www.taxmann.com/datafolder/Flash/Flashart4-11-09_6.htm