Non Resident Indians are those who are staying outside India for more than 182 days in previous years. Technically, NRIs are Indian nationals, staying outside India, but for the tax treatment, NRIs and foreign nationals are same as Income tax is calculated on the basis of residential status and not on the basis of citizenship. For all NRIs and foreign Nationals who are of Indian origin, they generally have bank accounts, properties, rentals and other Income in India for which they pay lot of taxes in the form of TDS, for ex, Bank withheld taxes on Interest arising on NRO accounts at higher rate. Taxes are withheld as these are taxable Income in India and NRIs/ foreign nationals have to pay taxes on all Income generating in India. Considering the fact, almost all NRIs/ Foreign Nationals are paying more taxes in the form of TDS and that can be claimed as refund. Also as a part of India, it is moral responsibility to disclose all the Income by filing taxes in India. Filing taxes in India does not mean that you have to pay taxes in India.
Why NRIs are required to file taxes in India: