Depreciation calculation: apply notional written down value and income-tax rates for managerial remuneration computation consistently. Depreciation for computing net profits for managerial remuneration must be calculated by reference to a notional written down value: for the first post amendment financial year derive that notional value from the book written down value as of April 1, 1956 (or immediately thereafter) after deducting normal pre amendment depreciation (excluding extra and multiple shift allowances for periods ending on or before December 27, 1960); thereafter apply income tax rates (including extra and multiple shift allowances for post commencement periods) to the notional written down value and reduce that value annually by the depreciation so computed.