Voluntary revision of customs entry allows post clearance self assessment and voluntary payment or refund claim subject to verification. Section 18A allows importers or exporters to revise cleared customs entries in prescribed form and time and requires self assessment of duty; voluntary payment of any shortfall with interest is permitted and excess duty claims are treated as refund claims. Proper officers may verify risk selected revisions and re assess where self assessment is incorrect. Revisions are barred where audits, searches, seizures or summonses have been initiated and intimated, where duty has already been reassessed or assessed under specified sections, or in other cases notified by the Board.