non resident-tax calculations

When a person is not a resident in india for any previous year, he is not legally liable to file his IT return in India(assuming he does not have any other income from India). A resident can file his IT return if taxable income is below the exemption limit and if he wants to claim refund of TDS which has been deducted from his income. In your case first of all, what is the need to file return in India when he does not have any income source from India.