Rectification of mistake: Assessing Officer may amend tax orders within statutory time limits, with notice and hearing if liability increases. Rectification of mistake: the Assessing Officer may amend an order to correct an apparent mistake within the statutory time limit from the end of the financial year in which the order was passed. Amendments may be made suo motu or on the assessee's request, but not insofar as matters have been considered and decided on appeal. Any amendment increasing liability, reducing a refund or otherwise adverse to the assessee requires notice and a reasonable opportunity of being heard, and must be made by a written order; reductions entail refunds, and increases specify sums payable.