08 April 2013
If you want to file your return manually then on the old forms change the Assessment year and then file. In case if you want to file efiling then filing with old forms doesn't accept by the system and doesn't valid.
So if you want to file manually then For A.Y 2013-14 return can be file in A.Y 2012-13 forms by changing assessment year. If you want to e file then you should be wait till the A.Y 2013-14 forms updating by the IT Department.
In one word for manual return filing filing of old itr for new year is possible but for e-filing it is not possible.