Value of supply under GST: transaction value plus prescribed inclusions; alternative valuation applies for related or non monetary transactions. The value of supply for GST is the transaction value paid or payable when price is sole consideration between unrelated parties, including specified additions such as non-GST taxes, amounts borne by the recipient on behalf of the supplier, incidental expenses (commission, packing), interest or late fees, and linked subsidies. Where parties are related or consideration is non-monetary, statutory valuation methods apply in sequence-open market value, value of like kind and quality, cost-plus margin, or reasonable residual methods-with special provisions for agents, pure agents, currency exchange, vouchers, insurance, second-hand goods, and gambling-related actionable claims. Discounts are excluded only when conforming to prescribed conditions.