Hello,As far as Indian Income Tax Laws concerned, primary requirements to file IT Return are Accrual/Arisal of Income in India, Having PAN and Being registered on Income Tax Site.As per section 139, an Individual needs to file Return of Income only if his Income during the Respective Financial Year exceeds Basic Exemption Limit i.e. INR 2,50,000 for FY 2018-19 (INR 5,00,000 for FY 2019-20).You can start filing IT returns once the FY get completed means from the very First Day the of Next Year till the Last Date which is called as Due Date, as applicable to you. (say, it's 31st July for Individuals). You can file it after Due Date also subject to Applicable Interest/Penalty.However, in India, IT Return Forms get changed each year to give the effect of Budget Amendments hence though you are eligible to start filing From 1st April as per Law, you need to wait till the Amended Forms get notified by Government.(Note: This answer is written Totally in General Context as IT Return Filing Criteria, Due Dates, etc. totally depends upon Nature of Person, Residential Status, Nature of Income and Other Various Factors as laid down in Income Tax Act, 1961 read with Income Tax Rules, 1962.)Happy Reading. Stay Tuned. Stay Updated.