Recital 31

(31)The granting of authorisations for several special procedures with a single guarantee and a single supervising customs office should be facilitated and there should be simple rules on the incurrence of a customs debt in these cases. The basic principle should be that goods placed under a special procedure, or the products made from them, are to be assessed at the time when the customs debt is incurred. However, it should also be possible, where economically justified, to assess the goods at the time when they were placed under a special procedure. The same principles should apply to usual forms of handling.