If a person wilfully fails to furnish in due time the return of his net wealth which he is required to furnish under sub-section (1) of section 14 or by notice given under sub-section (2) of section 14 or under sub-section (1) of section 17, he shall be punishable,—
(i) in a case where the amount of tax, which would have been evaded if the failure had not been discovered, exceeds one hundred thousand rupees, with rigorous imprisonment for a term which shall not be less than six months but which may extend to seven years and with fine;
(ii) in any other case, with rigorous imprisonment for a term which shall not be less than three months but which may extend to three years and with fine:
Provided that a person shall not be proceeded against under this section for failure to furnish in due time the return of net wealth under sub-section (1) of section 14—
(i) for any assessment year commencing prior to the 1st day of April, 1975; or
(ii) for any assessment year commencing on or after the 1st day of April, 1975, if—
(a) the return is furnished by him before the expiry of the assessment year; or
(b) the tax payable by him on his net wealth determined on regular assessment does not exceed three thousand rupees.