On appeal against the order of single Judge the Division Bench held that notice under section 148 of the Income-tax Act, 1961, is mandatory to reopen an assessment and reassess the income of the assessee and such a notice should have been issued by the competent Assessing Officer, who has jurisdiction. The jurisdictional Assessing Officer, who records the reasons for reopening the assessment as contemplated under sub-section (2) of section 148, has to issue notice under section 148(1). Only then, would such a notice issued under section 148(1) be a valid notice. The officer recording the reasons under section 148(2) of the Act and the officer issuing the notice under section 148(1) has to be the same person. Section 129 is applicable when in the same jurisdiction, there is a change of incumbent and one Assessing Officer is succeeded by another; and when once the initiation of reassessment proceedings is held to be invalid, whatever follows thereafter must also, necessarily be invalid. Accordingly   the first respondent who recorded the reasons for reopening the assessment under section 148(2), had no jurisdiction over the assessee, to issue notice dated March 28, 2018 under section 148(1). Though the files pertaining to the reassessment proceedings of the assessee were transferred, the second respondent had no authority to continue the reassessment proceedings under section 129 and hence, the notice dated December 14, 2018 issued by him was also invalid. The invalid notices so issued vitiated the entire reassessment proceedings initiated against the assessee. The notices and the consequent proceedings were invalid. (AY. 2011-12)