Payment of excise duty: duty must be paid on removal and registered persons must follow assessment, invoicing and record rules. The Central Excise Rules, 2001 establish that excise duty is payable on removal of excisable goods from factories or warehouses, with the assessee primarily responsible for self-assessment and payment subject to specified payment schedules, interest on delayed payment, and instalment forfeiture rules. The rules mandate registration, invoicing in triplicate, daily stock accounts, monthly returns, provisional assessment with bond where valuation is uncertain, CENVAT credit for returned goods, warehousing and export procedures, and enforcement powers including search, seizure, confiscation and penalties.