Assessment following search permits notices and reassessment of preceding tax years where undisclosed assets are identified. Assessment following search or requisition authorises the Assessing Officer to issue notices requiring returns and to assess or reassess the total income for the six assessment years immediately preceding the relevant assessment year, applying other provisions of the Act as far as may be. Pending assessments within that six year period abate on initiation of search or requisition but may be revived if an assessment under the search provisions is subsequently annulled.