Prior approval for assessments in search/requisition cases required before issuing assessment; approver need not provide a hearing. Assessments or reassessments from search or requisition proceedings cannot be finalized by an assessing officer below the rank of Joint Commissioner without the prior approval of the Joint Commissioner, except where the draft assessment requires prior approval of the Principal Commissioner or Commissioner; the approving authority is not obliged by this prior-approval mechanism to give the assessee a separate opportunity of hearing before approving the draft.