The AO reopened assessment after three years with approval from the Principal Commissioner. The Tribunal held that under section 151(ii), approval of the specified authority was mandatory beyond three years. Approval by the Principal Commissioner was invalid, and the reassessment notice and order were quashed as void ab initio, following the Supreme Court in UOI v. Rajeev Bansal (2024) 469 ITR 46 (SC). (AY. 2017-18)