Transaction value determines taxable supply valuation; includes taxes, incidental expenses and subsidies while excluding specified discounts. Valuation for taxable supplies is based on the transaction value: the price actually paid or payable where parties are not related and price is sole consideration. Value includes separately charged taxes and charges under other laws, amounts borne by recipient but payable by supplier, incidental expenses (commission, packing), charges for supplier activities at or before delivery, interest or late payment penalties, and subsidies directly linked to price included for the supplier receiving the subsidy. Discounts recorded on invoice or established by agreement with reversal of attributable input tax credit are excluded. Prescribed methods apply where transaction value cannot be determined and notified supplies follow prescribed valuation.