due date for filing return u/s 139(1)for f.y.2008-09 was 30th Sep 2009 for company, a person who is required to get his accounts audited and 31 July 2009 for any other person.
However, one can file Belated Return u/s 139(4) before the end of one year from the end of relevant assessment year.
For F.Y. 2008-09, the relevant assessment year is 2009-10 and therefore the last date for filing belated income tax return is 31/03/2011.