When, in the course of the assessment of the total income of any assessee, it is established that a loss has taken place which the assessee is entitled to have carried forward and set off under the provisions of sub-section (1) of section 72, sub-section (2) of section 73, sub-section (1) or sub-section (3) of section 74 or sub-section (3) of section 74A, the Assessing Officer shall notify to the assessee by an order in writing the amount of the loss as computed by him for the purposes of sub-section (1) of section 72, sub-section (2) of section 73, sub-section (1) or sub-section (3) of section 74 or sub-section (3) of section 74A.