Article 27 of the GCC Common VAT Agreement authorises a Taxable Person to adjust the value of the Tax imposed on a supply after its original date. This adjustment is permissible under three specific circumstances: the total or partial cancellation or rejection of a supply; a reduction in the value of the supply; or the total or partial non-collection of the consideration. For adjustments related to non-collection of consideration, the treatment must align with the specific conditions applicable to bad debts as stipulated by the domestic legislation of each individual Member State, providing a framework for post-supply VAT recalculations.