Customs exemption rate amendment alters the ad valorem tariff applicable to aseptic form fill seal machines under statutory powers. The Central Government, under section 25(1) of the Customs Act, 1962, amends Notification No. 96/90-Customs (20 March 1990) to substitute the previously specified ad valorem figure with a higher ad valorem figure, thereby changing the tariff rate applicable to aseptic form fill seal machines under the exemption notification.