Once you file the return, you can receive a ‘scrutiny notice’ for assessment under section 143 (2) of the Income-tax Act, 1961. Such a notice can be received within six months of the end of the assessment year. You can receive a notice for re-assessment under section 147 of the Act. Such a notice can be served within four years of the end of the assessment year if the income that is alleged to have escaped assessment is less than ₹1 lakh. If instead, such income is more than ₹1 lakh, the notice can be served within six years of the end of the assessment year. This effectively means seven years from the end of the financial year in which you have earned the income in question and hence, seven years is considered the time limit for maintaining your records in popular discourse.