Deemed income rule: companies with income below a proportion of book profit are taxed on a deemed book profit amount. Where a company's total income computed under the Act is less than thirty per cent of its book profit for the relevant previous year, its taxable total income shall be deemed to be thirty per cent of that book profit. Companies must prepare the profit and loss account under Parts II and III of Schedule VI, with depreciation calculated on the same method and rates as in the financial statements. Book profit is defined by specified addbacks and reductions, and specified carry forward and other tax provisions remain applicable.