If you export goods to be repaired or processed outside the European Union before being re-imported, you may be able to claim Outward Processing Relief (OPR). You claim relief from import duty on the value of the goods you originally exported or the difference in duty between the exported and re-imported goods. You need to be authorised to claim this relief.
For imports of goods that were previously exported but have not been processed overseas, you may be able to claim Returned Goods Relief (RGR). For example, you might use this if your customer rejects and returns the goods.
Depending on the circumstances, you may be able to claim full or partial relief from import duty, import VAT or both.
Read more about outward processing relief (OPR).