Sec. 154 of Income Tax Act, 1961— Rectification of mistake —It is a settled law that powers of the Assessing Officer to rectify an order u/s 154 are very limited and can be exercised only in a case where the Assessing Officer finds that a mistake apparent on record had occurred, however, in the case of a debatable issue or where the lengthy arguments are needed to decide the issue, powers u/s 154 can not be exercised to amend an already passed order and it has also been held time and again that powers u/s 154 cannot be exercised on change of opinion by the Assessing Officer on an issue relating to any admissibility of a claim - Power of rectification under section 254(2) can be exercised only when the mistake which is sought to be rectified is an obvious and patent; mistake which is apparent from the record, and not a mistake which requires to be established by arguments and a long drawn process of reasoning on points on which there may conceivably be two opinions and said proposition can be rightly applied to identical provisions of section 154 dealing with the rectification powers of the Income Tax Authorities, thus, the rectification order passed by the Assessing Officer and further confirmed by the CIT(A) cannot be held to be justified - - SHRI SANDEEP BHARGAVA V/s DEPUTY CIT - [2020] 27 ITCD Online 017 (ITAT-CHANDIGARH)