In principle, import duties should only be levied on those non-Union products that remain permanently in the customs territory of the Union and so enter its economic circulation.
Conversely, this means that usually there is not any justification for levying import duty if the imported products are going to be re-exported after having been used only temporarily.

It is for such cases that the arrangement of release for temporary admission has been set up. It provides for the complete or partial relief from import duties of non-Union products that

• are used temporarily and/or for a limited period for a specific purpose in the customs territory of the Union,
• will not be changed (apart form the normal depreciation caused by normal use) while they are being used, and
• had been, from the outset, intended for reexportation outside the customs territory.