18. Provisional assessment of duty. – (1) Notwithstanding anything contained in this Act but without prejudice to the provisions contained in 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 - (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. (3) The importer or exporter shall be liable to pay interest, on any amount payable to the Central Government, consequent to the final assessment order under sub- (2), at the rate fixed by the Central Government under 28AB from the first day of the month in which the duty is provisionally assessed till the date of payment thereof. (4) Subject the sub- (5), if any refundable amount referred to in clause (a) of sub- (2) is not refunded under that sub- within three months from the date of assessment of duty finally, there shall be paid an interest on such unrefunded amount at such rate fixed by the Central Government under 27A till the date of refund of such amount. (5) The amount of duty refundable under sub- (2) and the interest under sub- (4), if any, shall, instead of being credited to the Fund, be paid to the importer or the exporter, as the case may be, if such amount is relatable to - (a) the duty and interest, if any, paid on such duty paid by the importer, or the exporter, as the case may be, if he had not passed on the incidence of such duty and interest, if any, paid on such duty to any other person; (b) the duty and interest, if any, paid on such duty on imports made by an individual for his personal use; (c) the duty and interest, if any, paid on such duty borne by the buyer, if he had not passed on the incidence of such duty and interest, if any, paid on such duty to any other person; (d) the export duty as specified in 26; (e) drawback of duty payable under s 74 and 75. | 
