Q&A Why does the Spanish government say the Catalan referendum is illegal? Outside the EU, Catalonia would also have to establish its own border controls and customs service. The borders between Catalonia, Spain and France would become external borders of both the EU and the passport-free Schengen zone. An independent Catalonia would need to set up its own trading standards regulators and to start negotiating its own trade agreements. An independent Catalonia, however, would face an altogether greater problem: it would also have to exit the eurozone, at least temporarily.

Source: The Guardian October 09, 2017 14:01 UTC