Failure to furnish return of income attracts graded penalties, with prosecution barred in specified belated filing and low-liability cases. Wilful failure to furnish a return of income within the prescribed time under the filing provisions or by notice attracts graduated punishment under Section 479, with the sanction varying according to the amount of tax that would have been evaded if the default had not been detected. Prosecution is not to be initiated where a belated return is furnished under the specified provisions, or where a non-company taxpayer's assessed tax liability, after allowable reductions, does not exceed the prescribed threshold.