If your total Indian taxable income is over the basic tax threshold of Rs. 250,000, you are required to file tax returns in India. Note that in arriving at the above limit, only taxable income has to be considered. This means, incomes such as interest on NRE and FCNR deposits if any, will not be taken into consideration in order to arrive at the total taxable income. Similarly, any tax saving investments such as contributions to or deposits under some specified avenues such as insurance premium, investment in tax saving mutual funds, interest on long-term infrastructure bonds, PPF (where eligible) etc. have to be deducted. If the net result is above Rs. 250,000, then tax return has to be filed.
If TDS (withholding tax) has been applied to any of your income (especially NRO interest) the same has to be reduced from the net tax payable. If the TDS amount is more, then you can claim a refund.
The last date for filing returns for any Financial Year (April – March) is 31st July of the immediately succeeding Financial Year (FY). For example, for income earned in FY 2018-19, the tax return has to be filed by July 31st, 2019.