5 Taxable turnover

(1) For the purposes of this Act, taxable turnover means that part of dealers turnover arising during the tax period which remains after deducting therefrom -

(a) the turnover of sales not subject to tax under section 7 of this Act; and

(b) the turnover of sales of goods declared exempt under section 6 of this Act.

  (2) In the case of turnover arising from the execution of a works contract, the amount included in taxable turnover is the total consideration paid or payable to the dealer under the contract excluding the charges towards labour, services and other like charges, subject to such conditions as may be prescribed:

PROVIDED that where the amount of charges towards labour, services and other like charges is not ascertainable from the books of accounts of the dealer, theamount of such charges shall be calculated at the prescribed percentages.