This briefing considers the different ways in which one can understand who counts as a migrant in the UK and the implications of using different definitions.
There are many ways to interpret the term ‘migrant’
When counting migrants and analysing the consequences of migration, who counts as a migrant is of crucial importance. Yet there is no consensus on a single definition of a ‘migrant’. Migrants might be defined by foreign birth, by foreign citizenship, or by their movement into a new country to stay temporarily (sometimes for as little as one month) or to settle for the long term. In some instances, children who are UK-born or UK nationals but whose parents are foreign-born or foreign nationals are included in the migrant population.
While dictionary definitions sometimes distinguish ‘immigrants’ – people who are, or intend to be, settled in their new country – from ‘migrants’ who are temporarily resident, ‘immigrant’ and ‘migrant’ (as well as ‘foreigner’) are often used interchangeably in public debate and even among research specialists. In some scholarly and everyday usage, people who move internally within national boundaries are called migrants. No two definitions of migrant are equivalent, and their effects on our understanding of migration and its impact are significant.
There is no definition of ‘migrant’ or of ‘immigrant’ in law. From a legal perspective, there is a key distinction between people who are ‘subject to immigration control’, who need permission to enter or to remain in the UK and those who are not. While the UK was part of the EU, EU nationals were not subject to immigration control, although they were often described as migrants.
But if a migrant is not necessarily someone ‘subject to immigration control’, what alternative definitions exist?
Datasets for understanding migration in the UK use – and allow for analyses based on – different definitions of ‘migrant,’ as shown in Table 1. These vary along several dimensions.
Country of birth: Analyses of the impacts of migrants on the UK economy usually define migrants as ‘foreign-born’. These studies may rely on the Census, Labour Force Survey (LFS) and Annual Population Survey (APS), which are comprehensive sources of data on workers and labour markets in the UK. Although this is an intuitive definition of a migrant, many foreign-born people are also British citizens. They are not subject to immigration control, nor do they count as migrants when migration is defined by nationality.
Nationality: ‘Migrant’ alternatively may be defined as ‘foreign national’, for example, in Census data on the passport a person holds or LFS and APS data on self-reported nationality. This definition is viewed as more problematic than country of birth, as a person’s nationality can change. If self-reported, ‘nationality’ may be interpreted as describing an elective affinity dependent on social and cultural factors and personal feelings rather than legal status. UK nationals with other citizenships further complicate this picture, as often only one of their citizenships is captured in the data source.
Length of stay: In its analyses of migration into and out of Britain, the Office for National Statistics (ONS) uses the UN definition of ‘long-term international migrant’: “A person who moves to a country other than that of his or her usual residence for a period of at least a year [….] so that the country of destination effectively becomes his or her new country of usual residence (UN 1998)”. However, measuring migration according to this definition of ‘long-term migrant’ poses several challenges. First, for any given individual arriving in the UK, we do not know how long they will stay. This complicated pre-pandemic attempts to measure migration based on the International Passenger (IPS) survey, which asked respondents how long they intended to move. It also complicates more recent migration estimates based on administrative records since, to produce timely estimates, ONS must make assumptions about whether people who arrive in or depart from the UK are likely to do so for more than a year.
