Auxiliary customs duty on tariff-scheduled imports is additional to customs duties and governed by Customs Act procedures. An auxiliary customs duty is levied on goods listed in the Tariff Act's First Schedule as an additional charge based on value ascertained under the Customs Act; this duty is supplementary to all other customs duties. The provision contains a temporal cessation with saved past acts, and directs that the Customs Act's provisions, rules and regulations, including valuation, refunds and exemption mechanisms, apply to the levy and collection of the auxiliary duty to the extent practicable.