The last date of filing Income tax return was 31st July 2009 for financial year 2008-09. (individual not business income whose account has been audited.). But nothing to worry you can file it up to 31st march 2010 without any penalty.
But don’t think you can postpone your tax liability.You are liable to pay simple interest(1% for every month or part of a month of delay of filing of return) on your tax payable(after deducting TDS and advance Tax), if there is no tax payable then you can get satisfied(don’t need to pay any interest.)
You can deposit/file your return without any penal interest and penalty up to 31st march 2010.
Use the following instruction to file your ITR
before that Obtain Digital signature
