Proportionate input tax credit reversal verification: suppliers may rely on CA/CMA certificates or recipient undertakings to evidence reversal. The Circular clarifies that post-supply discounts excluded from taxable value require that the recipient has effected the proportionate reversal of input tax credit. Due to lack of portal verification, suppliers may obtain a CA/CMA certificate from the recipient detailing credit notes, related invoice numbers, ITC reversal amounts and the form/return evidencing reversal, with UDIN. For small-value discounts within a financial year, a recipient's undertaking with similar details is permissible. These certificates/undertakings are admissible evidence for tax officers and may be procured retroactively if required.