Less charge demand: procedure for issuing demand cum show cause notices to recover underpaid customs duty promptly. Failure to declare correct particulars affecting duty assessment-including value, description, classification, or applicable exemption notifications-creates an obligation on the importer or exporter to pay any duty short levied, non levied, short paid or non paid; officers are empowered to recover such unpaid duty by issuing a demand cum show cause notice linking liability to statutory valuation and classification used to determine customs duty.