If you don't have or earn any income in India then there is no need to file income tax return here. However, if the income accruing in India through, house property (immovable property), long term capital gains, rent and dividend or interest from investment in India, is beyond the threshold limit, you will have to file tax returns.
Here, too, you can claim certain deductions in certain heads like House Property and Short term capital gains.
For example, if you own a house in India which you have rented out, you can claim a standard deduction of 30% on the annual net rent received, that is, gross rent received minus municipal taxes paid, if any. The interest payment made every year for a home loan availed of in India or outside India is also allowed as a deduction in case of a rented property.
However if you have short term capital gains on equity shares or units of equity oriented mutual fund (even if less than Rs.1,50,000/-i.e. the basic exemption limit )yet you are liable to file ROI.
So, for 2011-12, an NRI (male and below 60 years) should file tax return in India if his income exceeds Rs1.8 lakh, while a person above 60 years, who earns more than Rs 2.5 lakh, will also have to file it. The due date for filing the return is 31 July of the year following the relevant tax year.