(b)shall make such amendment if any mistake is brought to its notice,-(i)by the assessee; or(ii)where the authority concerned is the [Chief Commissioner or Commissioner] [Substituted by section 72, Act 26 of 1988, for 'Commissioner' (w.e.f. 1-4-1988).] (Appeals), by the [Assessing Officer] [Substituted by Act 26 of 1988, section 72, for 'Income-tax Officer' (w.e.f. 1-4-1988).].