Case of Karam Chand Thapar & Bros, AAR West Bengal Ruling Dated 13th February 2025. AAR held that GST is not applicable to the arbitration cost awarded to the applicant, but 18% GST must be paid on the fees paid to arbitrators separately. It also ruled that if price of goods or services is increased and this increase is based on a contract made before GST came into effect, then supplier must issue a supplementary invoice or debit note. This invoice must be treated as a supply under GST, and GST will be payable on the increased amount.