Rectification of mistake :
Section – 100 . (1) With a view to rectifying any mistake apparent from the record, the Assessing Officer may amend any order passed by him under the provisions of this Chapter within one year from the end of the financial year in which the order sought to be amended was passed.
(2) Where any matter has been considered and decided in any proceeding by way of appeal relating to an order referred to in sub-section (1), the Assessing Officer passing such order may, notwithstanding anything contained in any law for the time being in force, amend the order under that sub-section in relation to any matter other than the matter which has been so considered and decided.
(3) Subject to the other provisions of this section, the Assessing Officer may—
(a ) make an amendment under sub-section (1) of his own motion; or
(b ) make such amendment if any mistake is brought to his notice by the assessee.
(4) An amendment, which has the effect of enhancing an assessment or reducing a refund or otherwise increasing the liability of the assessee, shall not be made under this section unless the Assessing Officer concerned has given notice to the assessee of his intention so to do and has allowed the assessee a reasonable opportunity of being heard.
(5) Where an amendment is made under this section, an order shall be passed in writing by the Assessing Officer.
(6) Subject to the other provisions of this Chapter, where any such amendment has the effect of reducing the assessment, the Assessing Officer shall make any refund, which may be due to such assessee.
(7) Where any such amendment has the effect of enhancing the assessment or reducing the refund already made, the Assessing Officer shall make an order specifying the sum payable by the assessee and the provisions of this Chapter shall apply accordingly.