law: Custom Act, 1962 
  18.
  
  Provisional Assessment of Duty. ľ 
  (1)
  
  Notwithstanding anything contained in this Act but without prejudice to the
  
  provisions contained in section 46
  (a) where the proper officer is satisfied that an importer or exporter
  
  is unable to produce any document or furnish any information necessary for the
  
  assessment of duty on the imported goods or the export goods, as the case may
  
  be; or
  (b) where the proper officer deems it necessary to subject any imported
  
  goods or export goods to any chemical or other test for the purpose of
  
  assessment of duty thereon; or
  (c) where the importer or the exporter has produced all the necessary
  
  documents and furnished full information for the assessment of duty but the
  
  proper officer deems it necessary to make further enquiry for assessing the  duty,the proper officer may direct that the duty  leviable on such goods may, pending the production of such
  
  documents or furnishing of such information or completion of such test or
  
  enquiry, be assessed provisionally if the importer or the exporter, as the case
  
  may be, furnishes such security as the proper officer deems fit for the payment
  
  of the deficiency, if any, between the duty finally assessed and the duty
  
  provisionally assessed.
  (2)
  
  When the duty leviable on such goods is assessed 
  
  finally in accordance with the provisions of this Act, then ľ
  (a) in the case of goods cleared for home consumption or exportation,
  
  the amount paid shall be adjusted against the duty finally assessed and if the
  
  amount so paid falls short of, or is in excess of the duty finally assessed,
  
  the importer or the exporter of the goods shall pay the deficiency or be
  
  entitled to a refund, as the case may be;
  (b) in the case of warehoused goods, the proper officer may, where the
  
  duty finally assessed is in excess of the duty provisionally assessed, require
  
  the importer to execute a bond, binding himself in a sum equal to twice the
  
  amount of the excess duty.