Special excise duty imposed on goods chargeable under excise law, payable in addition to existing excise liabilities. A statutory special duty of excise operates as an additional levy on goods chargeable under the Central Excises Act, excluding notifications that grant credit or reduction for duties already paid on inputs; the duty is payable in addition to other excise duties and, so far as practicable, the Central Excises Act and its rules (including refunds and exemptions) apply to its levy, collection and administration.