The European Community (EC) has rules for establishing the country of origin of imported and exported goods. You will need them to classify goods manufactured in more than one country.
As a customs union, the EC applies a common customs duty to goods imported from outside the EC. However, in practice, trade agreements between the EC and third countries, regional trade blocs and free trade areas determine the rate of duty and customs conditions. Some goods imported from or exported to certain countries will qualify for preferential treatment - eg lower or nil customs duty, whereas others will have non-preferential status and attract full excise.
This guide provides information on rules of origin and preferential trade agreements. It will help you prepare customs declarations to smooth the delivery and payment of goods and excise, as applicable.