Valuation of supply for post-supply discounts now depends on credit notes and input tax credit reversal. The valuation of supply rule under section 15 is amended for post-supply discounts. A discount is recognised only where the supplier has issued a credit note after the supply and the recipient has reversed the input tax credit attributable to the discount in accordance with section 34. The amendment links discount treatment to the credit-note mechanism and corresponding input tax credit reversal.