Failure to furnish income-tax return triggers prescribed penalties for late or due-date non-filing based on filing category. The substituted Section 271F establishes a two-tier penalty scheme for failure to furnish a return of income: a specified penalty where a person required to file under the primary filing obligation fails to furnish the return before the end of the relevant assessment year, and a lower specified penalty where a person required to file by the proviso to that obligation fails to furnish the return on or before the due date; liability is triggered by the filing requirement, timing of non-filing, and the relevant assessment year.