1. 1. The amount of the import or export duty shall be determined on the basis of those rules for calculation of duty which were applicable to the goods concerned at the time at which the customs debt in respect of them was incurred.
2. 2. Where it is not possible to determine precisely the time at which the customs debt is incurred, that time shall be deemed to be the time at which the customs authorities conclude that the goods are in a situation in which a customs debt has been incurred. However, where the information available to the customs authorities enables them to establish that the customs debt had been incurred prior to the time at which they reached that conclusion, the customs debt shall be deemed to have been incurred at the earliest time that such a situation can be established.
However, where the information available to the customs authorities enables them to establish that the customs debt had been incurred prior to the time at which they reached that conclusion, the customs debt shall be deemed to have been incurred at the earliest time that such a situation can be established.