Retail sale price based assessment confirms excise and NCCD computed after abatement; GST payable on transaction value including duties. Valuation for basic excise duty and NCCD uses a retail sale price based assessment with a 55% abatement as the prescribed measure for computing those duties; the abated value is not the manufacturer's prescribed sale price. GST and Compensation Cess are payable on transaction value, which includes basic excise duty and NCCD. Manufacturers may adjust retail price to account for duty increases. A statutory saving for tariff references preserves the validity of existing notifications referring to the repealed tariff Act.