Prosecution exemption for failure to file income tax return applies where return filed timely or tax liability is minimal. Prosecution shall not be launched where the assessee furnishes the return before expiry of the assessment year or files an updated return within forty eight months from the end of the assessment year. Alternatively, for non company taxpayers, prosecution is also excluded where the tax payable on total income determined on regular assessment, after reducing advance tax or self assessment tax paid before the assessment year's expiry and tax deducted or collected at source, does not exceed the prescribed de minimis threshold.