Following persons are required to file return of their income, duly filled in completely and correctly:

1) Individuals, Hindu undivided families, Association of Persona (AOP) Body of Individuals (BOI) (where individual shares of the members are known) and artificial juridical persons (such as deties of temples), having taxable income exceeding Rs. 1,00,000 (Rs. 1 ,35,000 in case of a resident women below 65 years or Rs1,85,000 in case of a senior citizen of 65 years or more).
Note: Filing of return is compulsory if the taxable income exceeds the basicexemption limit (as above) event if the tax payable is nil or refundable.

2) Non-resident Indians except1 those covered u/s 115AC and 115G having taxable income exceeding Rs.1,00,000

3) Individuals (including NRls), HUFs, AOPs/BOls and artificial juridical persons, having total income (before making deduction u/s 10A or 10B or 1OBA or Chapter VI-A) exceeding Rs.1,00,000 (Rs. 1,35,000 in case of a resident women below 65 year Rs. 1,85,000 in case of a senior citizen of 65 years or more). [Sec. 139(1) Fourth Provisio]

4) Societies and Trusts deriving income from property held for charitable or religious purposes or receiving voluntary contribution such purposes, and having total income (before giving effect of Sec. 11 and 12) exceeding Rs. 1 ,00,000. [Sec. 139]

5) A scientific research institution, news agency, association­ institution, fund or trust or university or other educational institution or any hospital or other medical institution or trade union claiming exemption u/s 10(21), (22B), (23A), (23B), (23C) 1[iiiad)/ (iiiae)/](iv)/(v)/(vi)/(via) or (24), whose total income, before claiming exemption, exceeds Rs. 1,00,000. [Sec. 139( 4C)] [5A. A university, college or other institution referred to u/s 35(1 )(ii)/(iii), not otherwise required to furnish return of income.] [Sec. 139( 4D)]

6) AOP/BOI where shares of the members are indeterminate or unknown, irrespective of income.

7) All partnership firms irrespective of income.

8) Co-operative society, company and local authority, irrespective of income.
Note: Filing of return by companies and partnership firms is mandatory .

9) Any person who has suffered a loss from business or profession or speculative business or capital loss, should furnish his return of income by the due date  otherwise the facility of set off and carry forward of loss shall not be allowed.

10) Units/undertakings claiming deduction u/s 10A 2[or 10B] are also required to furnish their return of income before the due date specified u/s 139(1).

11) Units/undertakings claiming deduction u/s SO-lA, 80-IAB, 80-IB or 80-IC are also required to furnish their return of income before the due date. [Sec. 80AC]

12) Any person who has paid tax (by way of TDS or advance tax) in excess of tax payable on total income, or who has paid tax but does not have taxable income, is advised to file his return for claiming refund of tax excess paid.

13) Persons who have not filed their return and have received a notice for assessment under section 142( 1) or reassessment u/s 148.
note : Any other person, who so desires, can file its return of income even if its come is below the maximum amount not chargeable to tax.