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HMRC internal manual

Customs Special Procedures Manual

Completion of End-use and discharging liability: request for extension to the period to assign the goods to the prescribed End-use

Traders should apply in writing for an extension. The period may be extended and be extended retrospectively, provided that the authorisation holder has adequate records to prove assignment to the prescribed End-use and the proper conduct of operations is assured. You should be satisfied that there is an intention to put the goods to the prescribed End-use, and the authorisation holder is not merely trying to defer payment of full rate of duty.

Delegated Regulation 2446/2015  Article 859.1