There is a controversy about the impact that Britain's withdrawal from the European Union will have at the end of the transition period on the border between the Republic of Ireland and Northern Ireland, in particular the impact it may have on the economy and people of the island were customs or immigration checks to be put in place at the border. It was prioritized as one of the three most important areas to resolve in order to reach the Agreement on the withdrawal of the United Kingdom of Great Britain and Northern Ireland from the European Union.