Its is mandatory for individuals, NRIs, partnership firms, LLPs, Companies, Trust to file income tax returns each year. Individuals and NRIs are required to file income tax return, if their income exceeds the exemption limit. Partnership firms are required income tax return - irrespective of amount of income or loss. All companies are mandatorily required to file income tax return. Finally, it is mandatory for most types of trust to file income tax every year, while some types of trusts are required to file return of income if its gross total income exceeds the exemption limit.