Reduction or waiver of interest payable under section 139In respect of assessment relating to an assessment year commencing on or before the first day of April, 1988, the Assessing Officer] may reduce or waive the interest payable under section 139 in the cases and in the circumstances mentioned below, namely :—
(i)   where the return of income is furnished by a person who has been treated under section 163 as an agent of a non-resident and is assessed in respect of the latter's income ;
(ii)   where the return of income is furnished by an assessee whose only source of income during the relevant previous year is a share in the income of an unregistered firm which has been assessed on its total income in respect of that previous year under clause (b) of section 183;
(iii)   where the return of income of a deceased individual is furnished by his legal representative and the legal representative satisfies the [Assessing Officer] that he had sufficient cause for not furnishing such return within time;
(iv)   where the return of income has been furnished in pursuance of a notice issued under section 148;
(v)   any case in which the assessee produces evidence to the satisfaction of the [Assessing Officer] that he was prevented by sufficient cause from furnishing the return within time :

Provided that the previous approval of the [Deputy Commissioner] has been obtained where the amount of interest reduced or waived, as the case may be, under clause (iv) or clause (v) exceeds one thousand rupees