Determination of non-resident income: Assessing officer may compute taxable income by turnover percentage or proportionate profits. If a non-resident's actual income from a business connection, property, asset, source in India, or money lent at interest brought into India cannot be definitely ascertained, the Assessing Officer may calculate the income by (i) applying a reasonable percentage of the relevant turnover, (ii) applying the proportion of such receipts to total business receipts against total profits and gains of the business, or (iii) any other method the Officer deems suitable.