Special duty of excise: surcharge on assessable excise for specified goods, additional to existing duties and collected under existing rules. When specified goods are assessed to duty under the Central Excises Act and applicable notifications, prescribed special duties of excise at stated percentage rates are levied on the total assessable amount. These special duties are additional to other excise duties, retained by the Union, and are to be levied and collected in accordance with the provisions and rules of the Central Excises Act, including those on refunds and exemptions. The principal charging provision includes a sunset clause with savings for prior acts.