Held that when the assessee was treating the loss and gains by different methods, the assessee should have explained it before the Assessing Officer during the course of scrutiny assessment proceedings under section 143(3) of the Act. However, there was nothing on record to show that the assessee had put up a note to the Assessing Officer with regard to treatment of losses as well as gains. When there was no material before the Assessing Officer with regard to marked-to-market gains, there was no occasion for him to apply his mind. Therefore, the question of change of opinion did not arise in this case. In our opinion, the Assessing Officer had not examined the issue of marked-to-market gains and had rightly issued notice under section 148 of the Act and completed the reassessment, which was valid. On merits  the Commissioner (Appeals) has not discussed the facts properly and had simply deleted the addition made by the Assessing Officer without giving any reason on the basis of any supporting evidence. The order of the Commissioner (Appeals) on this issue was to be set aside and the Assessing Officer was directed to consider the issue de novo in accordance with law. The Tribunal also held that the assessee was entitled to raise before the Assessing Officer the contentions that in case of marked-to-market gain was taxed, it may be allowed under section 10AA of the Act and the issue of book profits. (AY.  2013-14)