The material part of the Rule is : "In any case in which the Income tax Officer is of opinion that the, actual amount of the income, profits or gains accruing or arising to any person residing out of the taxable territories whether directly or indirectly. in the taxable territories. cannot be ascertained, the amount of such income, profits or gains for the purposes of assessment to income tax may be calculated on such percentage of the turnover so accruing or arising as the Income tax Officer may consider to be reasonable, or on an amount which bears the same proportion to the total profits of the business of such 942 person (such profits being computed in accordance with the provisions of the Indian Income tax Act) as the receipts so accruing or arising bear to the total receipts of the business, or in such other manner as the Income tax Officer may deem suitable." The rule in terms applies only when the Income tax Officer cannot ascertain the actual income, profits or gains accruing or arising to any person residing outside the taxable territories.