Value of supply: transaction value rule governs taxable value and identifies add backs and discount conditions. Value of supply is principally the transaction value where supplier and recipient are not related and price is sole consideration. The value must include specified additional amounts (non-GST taxes if separately charged, recipient-incurred supplier liabilities, incidental expenses, charges for supplier acts, interest/penalties for delayed payment, and subsidies directly linked to price). Discounts are excluded if invoiced at or before supply, or if post-supply discounts are contractually linked to invoices and the recipient reverses corresponding input tax credit. Where transaction value cannot be determined, or for notified supplies, value is to be determined as prescribed. Related persons and legal person definitions are provided.