(4)If any assessment under the provisions of this part is required to be made in the case of an assessee, in whose case a search is initiated or a requisition is made subsequently––(a)such pending assessment shall be duly completed;(b)assessment in respect of such subsequent search or requisition shall be made thereafter under the provisions of this part; and(c)if the period available for assessment in clause (b) is less than three months, such period shall be extended to three months from the end of the month in which the assessment, as referred to in clause (a) was completed.