S. 147 : Reassessment –Issuance of notice under S. 143(2) is mandatory -Failure to issue is not procedural irregularity –S. 292BB does not dispense with the issuance of any notice that is mandated to be issued under the Act, but merely cures the defect of service of such notice if an objection in such regard is not taken before the completion of the assessment or reassessment-Entire proceedings including any order is liable to be quashed though the assessee had participated in the course of the reassessment. [S.143(2), 148, 153(2), 292BB]