Modvat credit entitlement requires filing a Rule 57G declaration and provisional assessment where classification is disputed. Allowance of Modvat credit is contingent on filing a declaration under Rule 57G; assessees claiming nil rate should seek approval via a classification list. If the Department disputes the nil-rate claim, the assessee may resort to provisional assessment to avail Modvat credit towards provisionally assessed duty, with any credits adjusted on finalisation using the provisions of Rule 57E.