The Common Travel Area, or CTA, is a special travel zone covering the Republic of Ireland and the United Kingdom (as well as the Isle of Man and Channel Islands). British and Irish citizens can, at least in principle, travel passport-free within the zone.
Irish citizens can also take up long-term residence and access public services in the UK without immigration restrictions, and British citizens can do the same in Ireland. These reciprocal residence rights are sometimes also referred to as being part of the CTA.
The CTA dates back (in various forms) to the establishment of the Irish Free State in 1922. The Government of Ireland has summed up the basic principle (PDF) as being “that the Irish and UK Governments treat each other’s citizens in a similar manner to enable them to freely move between the two jurisdictions, and thereby reside and work in either jurisdiction, without the need for special permission”.
This briefing focuses on travel between the UK and Ireland, and on the rights of Irish citizens in the UK. It does not cover the Isle of Man or Channel Islands (which are not in the UK) or the rights of British citizens in Ireland.
The CTA allows for passport-free travel for British and Irish citizens – in theory
The UK and Ireland have for a long time arranged to minimise immigration controls on journeys between the two jurisdictions, particularly on the Northern Ireland land border.
A 2019 agreement states that this is to facilitate free movement only for citizens of the UK and Ireland. British citizens are not regarded as ‘non-nationals’ under Ireland’s immigration laws, and Irish citizens are largely exempt from UK immigration laws.
But because passport-free travel is only guaranteed for British and Irish citizens, in practice they may still need to bring one if going by air or sea to prove they have British or Irish citizenship. Passengers arriving in Ireland from Great Britain usually face border controls at the port or airport (although not the other way around). Airlines and ferry companies also require official photo ID as a condition of carriage.
People who need visas for travel to the UK or Ireland cannot rely on the CTA
The legal situation for citizens of other countries is more complicated. There is generally no mutual recognition of visit visas, apart from the British–Irish visa scheme for Indian and Chinese citizens. Someone who is required to get a visa to visit one country will usually require a separate visa for travel to the other country and cannot rely on the CTA (although Ireland unilaterally accepts UK visitor visas for certain nationalities).
The lack of routine border controls on the land frontier means that there is potential for abuse of the CTA for unauthorised migration. The British and Irish governments cooperate closely to guard against this, including through data sharing and the joint Operation Gull (PDF), but do not disclose the details of how this works. The immigration authorities of both countries conduct occasional checks within their own territory.
People who can visit Ireland without a visa, such as US or EU citizens, can usually do the same for the UK at present. But under the forthcoming scheme of electronic travel authorisations, such visitors will need to apply for permission before they can legally enter the UK. Irish citizens and legal residents are exempt, but there are some concerns about the impact on Northern Ireland tourism and a general hardening of the land border.
Irish citizens have unrestricted residence rights in the UK
As well as being able to travel freely to the UK, Irish citizens can take up long-term residence with no visa or work permit requirements, and are treated as though they have permanent immigration status or British citizenship. This means they can work and access public services without the restrictions that apply to other migrants.
The domestic legal basis for the rights of Irish citizens to healthcare, education and so on is complicated. The arrangements are outlined in a non-binding memorandum of understanding between the two governments but not confirmed in a formal treaty, which some feel it should be, especially following Brexit. But the special treatment of Irish citizens long predates joint membership of the EU, and the UK Government has been consistently committed to implementing it in practice for the past 100 years.
Related Commons Library briefings
Northern Ireland, citizenship and the Belfast/Good Friday Agreement