ATA Carnet clearance requires centralized register and monitoring; failure to submit re-export proof triggers customs duty recovery measures. Imports under ATA Carnet, exempt from duty under Notification No. 157/1990-Cus, must be entered in a centralized register at AC/DC (Import Group), ACC, NSCBI, Kolkata with specified fields. Consignments are examined only after register entry; the register serial number must be noted on the Carnet bill of entry copy and forwarded to AC/DC for monitoring closure within the notification's time limit. Failure to submit proof of re-export within the prescribed period will result in recovery of customs duty leviable as on the date of import.