EEC Customs Union
EEC Customs Union took effect on July 1, 1968, when the six European Economic Community members abolished customs duties on trade among themselves and adopted a single common external tariff, 18 months ahead of the Treaty of Rome schedule.
What happened and why it matters
A customs union means goods pay duty once at the outer border and then move freely inside, which is the basis of how brands distribute across Europe today. On the same day, the Common Customs Tariff replaced the six national tariffs, and the first Kennedy Round tariff cuts took effect. The union grew as new members joined and was deepened by the 1993 single market, which removed most remaining border formalities. For an importer, one EU customs declaration and duty payment can cover goods later sold in many member states, while shipments to non-members, such as the United Kingdom since Brexit, need separate customs entries.