If you do not file your income tax return on or before the due date then you will have to pay a late fee and interest. A late fee of Rs 5,000 is applicable for the late filing penalty. However, the late fee will be restricted to just Rs 1000 if the total income is less than Rs 5,00,000. Moreover, if tax is payable then interest will be applicable till the date of payment. Furthermore, you will receive an income tax notice asking you to file your income tax return. Hence, it is advisable to always file the ITR within the due date to avoid these hassles. You can later revise your ITR if you find any concerns in your ITR.