ITR

Which Assessment year? Generally penalty not be paid unless ordered by AO. For Interest u/s. 234A, 234B, or 234C  applicability refer article:  /articles/interest-u-s-234a-234b-and-234c-15276.asp

You are not required to pay any interest unless assesing officer ask you to do so.And max penalty he can levy is Rs.5000.But generally it is not levied.

I request you to kindly file a belated return u/s 139(4) and dont worry about it.

plz mention which assessment year you are asking for 

Belated return filing for AY 2014-15 not possible now, but if any refund due, can apply manually with condonation letter.

For AY 2015-16, file belated return before March 31, 2017. When nill tax return, no interest payable and even no penalty be charged.

For A.Y. 14-15 i suggest not to file ITR with Condonation Letter 

Bcoz A.O. can ignite Secruitny Order