Pursuant to search and seizure operations under section 132 conducted on 04.08.2000, the assessees filed block returns on 09.01.2001 admitting nil undisclosed income. The notice under section 143(2) was issued on 29.01.2002 but was admittedly served on the assessees only on 04.02.2002. The block assessments were completed and the additions were sustained up to the Tribunal. On appeal, the Court held that section 143(2) unequivocally mandates that the notice “shall be served” upon the assessee within twelve months from the end of the month in which the return is filed; issuance and service are distinct acts and mere issuance within the period is not sufficient. As the notice was served beyond the statutory period, the infirmity went to the root of the matter and the entire proceedings stood vitiated and were set aside. (AY. 2001-02)