Before filing the tax forms, you need to deposit the balance tax due and interest, if any. This amount is based on your tax liability for the year, after taking into account advance tax paid and tax deducted at source.
Lately the scope of tax deduction at source has been increased and includes salary, rent, interest, professional services etc. So, while preparing the tax returns and calculating the tax liability, you should take into account the tax amount already deducted on your behalf. Now, an easy way to do this is to refer to the 26AS statement. This statement is accessible on the NSDL site and is also available online on the websites of many banks.
According to a recent advice issued by the Income Tax Department, taxpayers should review their 26AS statements to check whether all the TDS deducted is appearing against their accounts or not. This would also facilitate faster processing of refunds, if any.