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Net migration in the UK

24 Aug 2018

This briefing provides an overview of net migration in the UK – defined as the difference between inflows and outflows of people moving for at least a year.

  1. Key Points
    • Net migration to the UK, the difference between immigration and emigration, was estimated to be 282,000 in 2017. This is down from a peak of 336,000 in the year ending June 2016, immediately before the EU referendum
    • Net migration of EU citizens rose substantially from 2012 onwards but fell sharply after the June 2016 EU referendum
    • Estimated non-EU net migration averaged 188,000 from 2008 to 2017, but there are significant uncertainties about the accuracy of these estimates
    • Work and study are the most common reasons for immigration to the UK, but their contribution to net migration currently cannot be accurately calculated


  1. Understanding the Evidence

    The analysis in this briefing is based on data from the Office for National Statistics (ONS) Long-Term International Migration (LTIM). The primary data source for the LTIM estimates is the International Passenger Survey (IPS), but LTIM estimates also include adjustments based on other sources, such as the Home Office data on asylum seekers, the Labour Force Survey and the Northern Ireland Statistics and Research Agency international migration estimates. To accurately understand and interpret LTIM data, it is important to be clear about its underlying definitions and limitations. The ONS uses the current international standard definition of a long-term international migrant to produce LTIM estimates: a person who moves to another country for at least one year (see “evidence gaps and limitations” below for further discussion). This excludes for example, tourism or short-term business related travel.

    There is significant uncertainty about the accuracy of some of the components of the IPS and LTIM figures. In particular, is has become clear that the emigration of non-EU students is not being correctly captured in the IPS survey but it is not yet clear to what extent data problems also exist in other categories (ONS, 2018). Fluctuations in IPS figures – which have significant margins of error – are not always visible in other data sources such as visa issuances. In its July 2018 data release, ONS noted the view that the IPS—which is commonly used in policy debates to scrutinise specific subcategories of migration such as non-EU students or EU workers—had been ‘stretched beyond its purpose’. It also cautioned against reading too much into year-on-year variations in specific components of net migration, because sampling error means that short-term changes in the estimates may represent statistical noise rather than a real trend.

    Note that some of the LTIM estimates for 2001-2011 have been revised following earlier problems uncovered for that time period, while others have not. In early April 2014 the ONS published their report on the ‘Quality of Long-Term International Migration estimates from 2001 to 2011’, in which they revised the numbers of total net migration for the years 2001 to 2011. Based on the revision, total net migration between 2001 and 2011 had previously been underestimated by 346,000. There is evidence that the underestimation was predominantly driven by an undercount of migration from the A8 Eastern European countries. However, a revised version of inflows and outflows as well as breakdowns by citizenship or reason for migration, etc., is not currently available. As a result, estimates relating to any breakdown of inflows, outflows, or different reasons for migrating will not match the total net balance.

    This briefing uses the term EU-15 to describe EU countries (other than the UK) that were already members of the EU in 2003. A8 refers to the eight East European countries that joined the European Union in May 2004 (Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, Slovenia). A2 refers to the countries that joined in 2007 (Romania and Bulgaria).

Net migration to the UK, the difference between immigration and emigration, was 282,000 in 2017, down from a peak of 336,000 in the year ending June 2016

The headline net migration figures include people of all citizenships, including British citizens leaving the country or coming from abroad. As shown in Figure 1, net migration rose from -13,000 in 1992 to 163,000 in 1999. In the mid-2000s there was a significant increase in net migration that coincided with the 2004 EU enlargement.

Net migration fell between 2010 and 2012, from 256,000 to 177,000. This period coincided with several policy measures designed to restrict study, work and family migration, as part of the Conservative Party’s goal of reducing net migration to the ‘tens of thousands’. The lowest estimate of net migration during this period was 154,000 in the year ending September 2012.

Levels started to increase again from 2013 onwards, however. This increase took place at a time when the UK economy was starting to recover from the economic crisis, but some of the key origin countries for migrants to the UK (particularly in Southern Europe) were still experiencing high unemployment.

The highest level of net migration recorded is currently 336,000, a level reached in mid-2015 and again in the year ending June 2016, immediately before the EU referendum. In the year after the referendum (the year ending June 2017), net migration recorded its largest ever single-year fall, although part of this decrease was driven by a statistical anomaly in the measurement of non-EU students (ONS, 2018). The provisional estimate of net migration was 282,000 in 2017.

Figure 1

Source: ONS LTIM data

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Net migration of EU citizens rose substantially from 2012 onwards but fell sharply after the June 2016 EU referendum

Figure 2 shows net migration for EU vs. non-EU citizens, as well as total net migration (the latter also includes British citizens).

Before 2004, net migration of EU citizens fluctuated but remained below 35,000 each year. It saw a sharp increase after EU enlargement, from 2004 to 2007 – when it reached 127,000, then fell around the time of the financial crisis (2008-2012), to a low of 58,000 in 2009. A second increase in EU net migration took place from 2013 onwards, peaking at 189,000 in the year ending June 2016. EU net migration then fell sharply following the EU referendum and stood at 101,000 in 2017.

The decline in EU net migration between the year ending June 2016 and the year ending December 2017 was spread across all of the three main EU origin groups – EU15, A8 and A2. During this period net migration fell from 84,000 to 46,000 for EU15 citizens, from 42,000 to 6,000 for A8 citizens, and from 62,000 to 40,000 for A2 citizens.

Figure 2

Source: ONS, LTIM table 2.00. Note: total net migration figures for 2001-2011 have been revised upwards (see ‘understanding the evidence’, above; country breakdowns have not been revised and so may understate net migration levels

Adding together EU and non-EU figures does not lead to total net migration, because the latter also includes British citizens. British citizens are the only group characterised by continuous net emigration since 1991 (i.e. negative net migration). Peaks in British net emigration occurred in 2004 (104,000) and 2006 (124,000). In 2017, there were 46,000 more British citizens moving abroad than coming to live in the UK.

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Estimated non-EU net migration averaged 188,000 from 2008 to 2017, but there are significant uncertainties about the accuracy of the estimates

In 2017, estimated net migration of non-EU citizens was 227,000. These figures have fluctuated over time (Figure 2, above), averaging 188,000 over the ten year period from 2008 to 2017.

Although this suggests that net migration of non-EU citizens in 2017 was roughly double net migration of EU citizens—despite policies introduced since 2010 to restrict non-EU migration—there are reasons to be cautious about making this comparison. Other data sources suggest that net migration of non-EU citizens may in fact be lower than the headline IPS figures suggest.

Preliminary analysis from the ONS published in July 2018 compared the IPS figures, which are used to calculate net migration, with Home Office data on visas issued and entries or exits from the UK. It found that while estimated immigration inflows in the two sources were similar, the IPS showed much less emigration than the Home Office data (ONS, 2018). The gap was driven primarily but not exclusively by non-EU students, whose emigration appears to be significantly undercounted in the net migration figures.

Similarly, a different source of data on migrants in the UK – the Annual Population Survey – suggests that the non-EU born population of the UK has not increased as much as one would expect if net migration had averaged 188,000 per year for 10 years (see Portes, 2018 for a full discussion). While the two sources measure slightly different things and cannot be compared like for like, it is noteworthy that the non-EU born population of the UK only increased by an estimated 1,044,000 from 2008 to 2017, i.e. on average 104,000 per year (ONS, 2018b).

Exactly what this means for estimates of other categories, notably EU net migration, remains uncertain.

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Work and study are the most common reasons for immigration to the UK, but their contribution to net migration currently cannot be accurately calculated

As people often move for a variety of reasons, it can be difficult to categorise migrants based on their reasons for migrating to the UK (see our ‘Mixed Migration: Policy Challenges’ primer for a discussion of mixed migration motivations). It is not hard to imagine, for instance, that someone might move to the UK to join their spouse, work part time and also study. It is therefore important to keep in mind that while the ONS records the categories discussed below as mutually exclusive categories, this will not always be the case in practice.

In 2017, 269,000 people moved to the UK for at least one year for work related reasons (including British citizens). These people either had a definite job (30% of all immigrants) or came to look for a job (12% of all long-term arrivals). Work is now the most common reason for migrating to the UK, a shift from the 2009 to 2012 period when formal study occupied this position.

In 2017, the second most common reason for moving to the UK was study, which made up 30% of long-term immigration. This number has fallen from 238,000 in 2010 to 191,000 in 2017. Study migration is driven by non-EU citizens, while work migrants are more likely to be EU citizens.

The number of people who came to accompany or join a family member was substantially lower, at 79,000 people or 13% of total inflows in 2017. Family migration levels have remained relatively stable over the past 10 years in absolute terms; this means that its share of total long-term immigration has declined during that period.

Figure 3

Source: ONS LTIM table 2.04

Since 2012, the ONS has collected data on emigration from the UK by initial reason for migration. In theory, this should make it possible to understand which categories of migration – work, family, study, or other reasons – have contributed most to net migration.

However, as noted above, estimates of the number of non-EU students who subsequently emigrate are now recognised not to be accurate (ONS, 2018). It is not yet clear to what extent this means that other categories of net migration (e.g. of people arriving for work and family) are also inaccurate.

These problems with the data make it important not to draw strong policy conclusions from the net migration figures on specific routes. It also means that there is currently no robust way to remove international students from the government’s net migration target, as some stakeholders have proposed—at least if the target continues to be based on IPS figures.

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Evidence gaps and limitations

The ONS is currently reviewing the quality of migration statistics, including IPS estimates, and plans to make greater use of administrative data such as Home Office visa records and exit checks. This programme of work aims to improve the understanding of why IPS figures are not always consistent with other sources, such as the Annual Population Survey or visa data (ONS, 2018). This is a complex exercise, however, because different data sources are collected in different ways and often measure slightly different things; as a result, there are often several possible explanations for discrepancies between data sources and it is not straightforward to determine which is responsible.

To date, efforts to reconcile different sources of migration data have focused on non-EU migration, since there is a richer set of other data sources available here (e.g. Home Office visa data). There may be implications for EU migration estimates (see e.g. Portes, 2018), but these implications are not yet known.

In the meantime, it is not sensible to use the IPS and net migration figures for detailed scrutiny of different categories of migration and their contribution to net migration overall. Using these data to draw policy conclusions about how to treat different types of migration (for example, to draw up a plan for reducing net migration to a given level), would be misleading.

It is also important to note that the IPS inflow and outflow estimates are not designed to account for short-term migration. This is one reason why immigration figures from the IPS are, for some nationalities, smaller than the number of National Insurance Number registrations. The International Passenger Survey asks individuals about their intended length of stay in the UK and abroad. People are classified as ‘long-term migrants’ if they intend to move for more than 12 months. Migrants’ plans for the future, e.g. the intention to stay in the UK for more than 12 months, may or may not be realised, however. To address this, the ONS adjusts the data for ‘visitor switchers’ (i.e. those whose original intention was to stay for less than one year but who subsequently stay longer) and for ‘migrant switchers’ (i.e. those who intended to stay for more than twelve months but left within a year). However, making the adjustment is methodologically challenging, and based on currently available data sources it is not possible to be certain how much switching is actually taking place and what the implications of this are for the overall net migration figures (ONS, 2018).

Thanks to Ann Singleton for helpful comments and suggestions in an earlier version of this briefing.


Recommended citation

Sumption, Madeleine and Carlos Vargas-Silva. “Long-Term International Migration Flows to and from the UK.” Migration Observatory briefing, COMPAS, University of Oxford, UK, July 2018

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