The customs union (Articles 28-29 of the Treaty on the Functioning of the European – TFEU) is an essential foundation of the EU and of its single 28-country market. For the single market to function properly, EU countries have agreed standardised rules that are applied in a uniform manner by all 28 EU customs administrations.
There are no customs duties at the EU Customs Union’s internal borders. All goods circulate freely within the customs union area, whether they are made in the EU or imported from outside.
A new EU Customs Code which simplifies rules and procedures for customs and makes trading more efficient was adopted in 2013. Once it applies, in May 2016, it will greatly simplify and streamline EU customs procedures.
Efforts are also under way to improve customs risk management and the security of the supply chain, as well as to develop procedures to improve the efficiency of customs in enforcing health, safety and environment rules.
Source: EUR Lex Glossary