Assessing Officer definition clarified for reassessment proceedings, excluding faceless assessment units and overriding contrary schemes or orders. The term Assessing Officer for sections 148 and 148A means, and is deemed always to have meant, an Assessing Officer other than the National Faceless Assessment Centre or any assessment unit referred to in section 144B(3). The clarification overrides any contrary judgment, order, decree, section 151A, or scheme framed thereunder, and removes doubts about the authority competent for reassessment-related functions.