Transaction value determines taxable supply valuation; inclusions, exclusions and specified discount conditions govern taxable value calculation. Value of a supply is the transaction value where supplier and recipient are not related persons and price is the sole consideration. The value must include certain taxes and charges when separately charged, amounts borne by recipient on supplier's behalf, incidental expenses, interest or penalties for delayed payment, and subsidies directly linked to price. Discounts recorded on invoice or arising under pre-existing agreements (with reversal of attributable input tax credit) are excluded. Where transaction value cannot be determined, value follows prescribed methods and notified supplies are valued as prescribed.