Regulatory duty of customs augments existing customs duties and applies by notification under Customs Act provisions. The regulatory duty of customs is an additional levy on goods in the Tariff Act First Schedule, charged from dates notified by the Central Government and calculated by reference to either a proportion of the tariff rate or a proportion of the goods' value, whichever yields the higher duty. The levy is in addition to other customs duties and, as far as possible, is governed by the provisions, rules and refund or exemption mechanisms of the Customs Act; notifications imposing the duty must be laid before Parliament.