Under Irish law, all British citizens – including Manx people and Channel Islanders, who are not entitled to take advantage of the European Union's freedom of movement provisions – are exempt from immigration control and immune from deportation.[60] They are entitled to live in Ireland without any restrictions or conditions.[61] They have, with limited exceptions,[62] never been treated as foreigners under Irish law, having never been subject to the Aliens Act 1935 or to any orders made under that Act.[61] British citizens can thus move to Ireland to live, work or retire and unlike other EU citizens, they are not required to demonstrate having sufficient resources or have private health insurance in order to retire. This is due to the fact that British citizens are also entitled to use Irish public services on the same basis as Irish citizens in Ireland.[61]
en.m.wikipedia.org/wiki/Common_Travel_Area