The assessee challenged the validity of the assessment on the ground that the notice under section 143(2) was not issued in any of the three formats prescribed by the CBDT Instruction dated 23 June 2017. The Tribunal held that the issue involved a pure question of law going to the root of the assessment. Since the notice did not conform to the mandatory prescribed format, the assessment under section 143(3) was invalid, and the consequential revision under section 263 was also without jurisdiction and liable to be quashed. (AY. 2018-19).