I am returning goods to the seller

Return of goods, i.e. cancellation of the purchase, means that the goods are permanently returned to the seller.

If you return the goods to the territory of the EU, you do not need to deal with Customs.  

If you return the goods to an area outside the territory of the EU or to the customs territory of the EU, but outside the fiscal territory of the EU, you may get a refund of the import duties and taxes that you have paid for the goods. If this is the case, submit an export declaration and apply for amendment of the customs clearance decision as follows:

• Submit an export declaration on the goods before the goods are returned to you.
• Apply for amendment of the customs clearance decision within 90 days of the declaration.

When submitting the export declaration to Customs you will need

• an order confirmation, invoice or receipt indicating the value of the goods
• a free form statement explaining that you are returning the goods
• the commodity code of the goods at the level of eight digits.

Please note that, in addition to the export declaration submitted to Customs, the transport company may need its own declarations. Please check this with the transport company.