29 April 2013
Those returns which are filed u/s 139(1) only possible to file revised return u/s 139(5) upto the due date u/s 139(4).
I.e for example if you filed For A.Y 2012-13 return of income with in 31-7-2012(i.e for this case due date u/s 139(1) is 31-7-2012) then you can file revise return u/s 139(5) upto 31-3-2014.
In simple a return which is filed with in due date as per section 139(1) can be revise upto expiry of one year for the end of such assessment year or completion of assessment for such year which is before.
So for the above example eventhough you have time to revise upto 31-3-2014 but assessment has been completed before to the date of filling of revised return then you can't file revise return.
In one word revised return can be file upto one year from the end of such assessment year or completion of assessment year which is earlier.