Taxable turnover defined as turnover after deducting non taxable and exempt sales; works contract valuation excludes labour and service charges. The provision defines taxable turnover as the dealer's turnover remaining after deducting sales not subject to tax and sales declared exempt. For works contract turnover, taxable turnover is the total consideration payable excluding charges towards labour, services and other like charges, subject to prescribed conditions, with unascertainable charges to be calculated at prescribed percentages.