Population by country of birth and nationality estimates: frequently asked questions

1.1 What period do the latest estimates cover?

The latest available estimates, released on 24 August 2017, are for the period January 2016 to December 2016.

1.2 What is available?

Estimates derived from the Annual Population Survey (APS) provide data on the population by country of birth and nationality; available from 2004 to 2016 at national and sub-national levels. Estimates for 2000 to 2003, derived from the Labour Force Survey (LFS), are also available separately.

The published datasets are produced alongside a statistical bulletin. It should be noted that the following country groups are referred to throughout the publication:

• EU and EU27 consist of the countries in the EU14, EU8, EU2, Malta, Cyprus, and Croatia (from 1 July 2013). The UK is not included in this group

• EU14 consists of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, the Netherlands, Portugal, Republic of Ireland, Spain and Sweden.

• EU8 consists of the eastern European countries that joined the EU in 2004: Czech Republic, Estonia, Poland, Hungary, Latvia, Lithuania, Slovakia and Slovenia.

• EU2 consists of the two countries that joined the EU in 2007: Bulgaria and Romania.

• non-EU consists of all those countries not in the UK or EU27 groups, this group excludes Croatia from 1 July 2013 when it joined the EU; estimates for non-EU have also been split geographically to provide estimates for Asia and the Rest of the World.

1.3 Where can I find them?

All estimates can be found on the Population by country of birth and nationality data section on our website.

2.1 What are the most common overseas countries of birth and nationalities resident in the UK?

The latest data for year ending December 2016, show the most common non-UK country of birth was Poland (911,000 Poland-born residents) and the most common non-British nationality in the UK was Polish (1 million Polish nationals).

2.2 Does being at the top of the country of birth and nationality tables indicate a recent large immigration into the UK?

Not necessarily. These estimates provide an insight into the resident population of the UK by country of birth and nationality, some of whom will have been living in the UK for many years. Changes from one reference period to another reflect not only immigration, but also emigration, births and deaths.

2.3 How has the EU accession impacted on the size of the migrant population in the UK?

For the year ending December 2016, there were an estimated 1.4 million EU8-born residents in the UK. This was an increase of 145,000 from year ending December 2015 (a statistically significant increase). Since 2004 (the year of accession), there has been an increase of 1.3 million EU8-born residents in the UK (an increase that is also statistically significant).

A further two countries; Romania and Bulgaria (EU2), joined the EU on 1 January 2007. Migrants from Bulgaria and Romania coming to the UK had been subject to transitional employment restrictions. These restrictions ended on 1 January 2014, which may have impacted on migration flows to the UK from Bulgaria and Romania. For the year ending December 2016, there were an estimated 395,000 Romanian and Bulgarian born residents in the UK. The margin of error (or confidence interval) surrounding this figure is plus or minus 30,000. See Section 4.2 for more information on confidence intervals. This represents a 37% increase of 107,000 residents since year ending December 2015 (288,000). This increase is statistically significant.

2.4 What proportion of the population was born outside the UK?

Latest figures for year ending December 2016 show the number of UK residents who were born abroad was 9.2 million. This accounts for 14% of the current UK resident population as recorded by the Annual Population Survey (APS) and represents an increase of 3.9 million since 2004. A total of 5.6 million came from outside the EU and the remaining 3.5 million from within the EU.

2.5 What proportion of the population are non-British nationals?

Latest figures for year ending December 2016 show the number of UK residents who were non-British nationals was 6.0 million. This accounts for 9% of the current UK resident population as recorded by the Annual Population Survey (APS) and represents an increase of 3.0 million since 2004. A total of 2.4 million were nationals of countries outside of the EU and 3.6 million were nationals of countries within the EU.

It should be noted that calendar year 2016 was the fourth year in a row where the number of EU nationals resident in the UK was higher than the number of non-EU nationals. Prior to 2013 this had not occurred at any point for which we have data.

2.6 How many UK residents with a non-UK country of birth have British nationality?

In 2016, there were 3.6 million British nationals whose country of birth was outside the UK. This represents 39% of the non-UK born population in the UK. It should be noted that this estimate will include both those that have moved to the UK and applied to become British nationals, as well as those that were born abroad but had British nationality at birth (for example, people whose parents were in the military services and were based abroad when they were born).

3.1 What are these estimates based on?

The Labour Force Survey (LFS) is a survey of households living at private addresses in the UK. Its purpose is to provide information on the UK labour market but it also includes other variables, such as country of birth and nationality, which can be used to produce these estimates. The Annual Population Survey (APS) combines results from the LFS and the English, Welsh and Scottish Labour Force Survey boosts.

Each quarter’s LFS sample of 40,000 households is made up from 5 “waves”, each of approximately 8,000 households. Each wave is interviewed in 5 successive quarters, such that in any one quarter, one wave will be receiving their first interview, one wave their second and so on, with 1 wave receiving their fifth and final interview. Interviews from waves 1 and 5 are included in the APS so that there is no sample overlap.

In some areas of the UK the boost makes up the bulk of the APS dataset, with a smaller contribution from the main LFS. The boost has a 4-year wave structure instead of the 5-quarter wave structure in the main LFS; after the initial interview, sampled households are interviewed three more times on an annual basis. Therefore the boost for these areas may be slower to react to a change in migration patterns than the main LFS and the speed with which the APS sample responds to changes in the household population may vary across the UK.

APS datasets are produced quarterly with each dataset containing 12 months of data. There are approximately 300,000 persons per dataset. More accurate estimates are available from the APS than from the main LFS.

3.2 Is the whole population sampled by the Annual Population Survey (APS)?

The Labour Force Survey (LFS) and the APS are household surveys. As such they do not cover most people living in communal establishments, some NHS accommodation, or students living in halls of residence who have non-UK resident parents. For a more comprehensive estimate of the population, please refer to our mid-year population estimates.

3.3 What is the difference between nationality and country of birth?

Nationality refers to that stated by the respondent during the interview. Country of birth is the country in which they were born. It is possible that an individual’s nationality may change, but the respondent’s country of birth will always remain the same. This means that country of birth gives a more accurate estimate of change over time.

There are two main reasons for differences between nationality and country of birth:

• as those born abroad remain in the UK they may apply to become British nationals.

• some people born abroad have British nationality at birth; for example, this may be the case for people whose parents were in the military services and were based abroad when they were born.

3.4 How do these data relate to estimates of Long-Term International Migration (LTIM)?

Estimates of the UK population by country of birth and nationality are not directly comparable to estimates of Long-Term International Migration. This is mainly because of the definitional differences between the two surveys used to estimate migrant flows (International Passenger Survey (IPS)) and the foreign resident population (Annual Population Survey (APS)).

A discussion on the differences between international migration data from the Labour Force Survey (LFS) and APS and International Passenger Survey (IPS) and LTIM can be found in the report: Note on the differences between Long-Term International Migration flows derived from the International Passenger Survey and estimates of the population obtained from the Annual Population Survey: December 2016.

3.5 How do these data relate to the population estimates?

The mid-year population estimates (MYEs) do not contain a breakdown of the population by country of birth or nationality, but are used to weight the Annual Population Survey (APS) sample results to produce estimates of the household population.

The MYEs cover the usually resident population; namely those who have lived in the UK for 12 months or more and includes those in communal establishments, whereas the APS does not include those in communal establishments and includes those who have been here for less than 12 months. The MYEs are point-in-time estimates, whilst the APS is an annual rolling quarterly estimate based on the Labour Force Survey (LFS). For these reasons the sum of those born in the UK and outside the UK may not match the MYEs.

We are, however, publishing a research paper and associated statistics on 25 August 2017 focusing on estimates by ethnicity, country of birth, and nationality that align with the mid-year population estimates.

3.6 Have all the published tables been revised according to the latest mid-year population estimates?

When Labour Force Survey (LFS) and Annual Population Survey (APS) datasets are produced, they are weighted to be in-line with the latest mid-year population estimates. Every 2 years the back-series of datasets are reweighted following release of the next set of mid-year population estimates. Data on the population by country of birth and nationality are produced based on the latest weighted dataset available, so that they reflect the population at that point in time.

Office for National Statistics (ONS) will not routinely re-publish population data online as a result of the reweighting exercise. However, in October 2014 and March 2015 respectively, the LFS and APS were reweighted based on results of the 2011 Census. In July 2015, ONS released reweighted datasets for calendar years 2004 to 2013. In August 2015 a research report was published comparing the pre- and post-reweighted data and how it has affected the estimate of the population of the UK. The reweighting exercise led to an increase in the estimate of the population of the UK of 538,000 between 2004 and 2013.

3.7 Have results from the 2011 Census been compared with the country of birth and nationality publication?

It is important to note that all figures contained in the population by country of birth and nationality publication refer to estimates from the Annual Population Survey (APS) and do not refer to any data collected as part of the 2011 Census. However, Office for National Statistics (ONS) has released a report on detailed country of birth and nationality analysis from the 2011 Census of England and Wales. Findings from this report are similar to findings from the APS data. The census report stated that 13.0% of the usually resident population of England and Wales was born abroad and 7.4% were non-British nationals. It also stated that the most common non-British nationality was Polish.

Further data from the 2011 Census are available on the Census data section of the ONS website.

3.8 Have any provisions been made for migrants staying illegally?

Anyone who enters or stays in the UK illegally would not be sampled by the the Labour Force Survey (LFS) or Annual Population Survey (APS) unless they opt to take part upon being approached. However, the survey does not ask information on the respondent’s legal status so therefore we do not hold statistics on illegal migrants. No British government has ever been able to produce an accurate figure for the number of people who are in the country illegally.

By its very nature it is impossible to quantify accurately the number of people who are in the country illegally. For this reason Office for National Statistics (ONS) does not produce estimates on the size of the illegal migrant population. In June 2005, the Home Office published the outcome of an assessment of whether methods used in other countries to estimate the size of the illegal population could be applied to the UK. The outcome estimated that the total unauthorised migrant population living in the UK in 2001 was 430,000. Please see the following reports for more information: 29/05 - Sizing the unauthorised (illegal) migrant population in the United Kingdom and 58/04 - Sizing the illegally resident population in the UK.

A more recent report has been written by the London School of Economics (LSE), Economic impact on the London and UK economy of an earned regularisation of irregular migrants to the UK, which estimates that in 2007 the number of “irregular” migrants was 533,000. A more recent report has been published by Migration Watch who have updated the LSE report based on several different assumptions.

3.9 What measures are available on estimating the legally resident population?

The Annual Population Survey (APS) provides data on the population by country of birth and nationality of the UK resident population, but information on the current immigration status of the population is not available. Immigration statistics, which provide information on applications to live, work, and study in the UK are published by the Home Office, however, there is no information available on whether those granted visas are resident in the UK. Therefore, there is no measure that directly records the legally resident population.

3.10 How does the size of the UK migrant population compare with other countries?

For information on the migrant population in other countries please see the Eurostat website, or the United Nations website.

3.11 Do you have data on the numbers of UK migrants living abroad?

A report was published in January 2017 that explored statistics available to estimate the number of British migrants living in Europe. There will be a further series of reports published within the next year to update this report, focusing firstly on Spain, followed by EU8, France, EU2, Ireland, Germany, Mediterranean countries and northern Europe.

Alternatively, an individual country breakdown for Europe can be found on the Eurostat website. The US Census Bureau website contains a list of International Statistical Agencies.

4.1 Why should the public have confidence in these population estimates by country of birth and nationality?

The Annual Population Survey (APS) is the largest household survey in the UK (other than the census and Census Coverage Survey) and is the most reliable source of data on the UK population when split by country of birth and nationality.

The estimates published are deemed National Statistics. They are produced in accordance with the Code of Practice for Official Statistics, the principles of which can be found on the UK Statistics Authority website.

4.2 How accurate are these estimates? What are confidence intervals and standard errors?

A confidence interval provides an estimated range of values in which an actual data value is likely to fall. The confidence interval provided is a 95% interval. This means that, across the dataset as a whole, the confidence intervals are expected to contain the true values around 95% of the time.

4.3 Why are methods of disclosure control and data suppression used?

Cells in a table based on a small number of respondents are more likely to breach confidentiality. The same cells are also likely to be unreliable. Confidentiality protection is provided by releasing only weighted estimates and by suppressing the values for unsafe cells. Information on the exact number of sample respondents is restricted.

The effect of disclosure control on the quality of data that can be released is very small because data that are disclosive are generally also of low quality. Footnotes are supplied to advise users to be cautious when making inferences from estimates with large confidence intervals when compared with the estimate.

5.1 How do I obtain data for previous years that are not currently published on the international migration landing page?

The Population by Country of Birth and Nationality data section on our website has estimates for calendar years January to December 2004 to 2016, based on the Annual Population Survey (APS), as well as estimates for 12-month periods covering March 2000 to February 2004, based on the Labour Force Survey (LFS).

To obtain data prior to 2000 please contact the LFS data service (socialsurveys@ons.gov.uk) who can assist with time series requests.

5.2 How often are the Annual Population Survey (APS) data published and what is published?

Office for National Statistics (ONS) consulted on several aspects of our international migration outputs, including the publication frequency of the Population by country of birth and nationality tables. As a result, the publication had been moved to an annual publication accompanied by a statistical report. However, ONS will also be releasing a dataset covering the period July 2016 to June 2017 in November 2017 and may continue to publish mid-year datasets in future years. Table 1 shows the timeframe for planned publications.

Table 1: Release dates of Population by country of birth and nationality tables

5.3 Is it possible to obtain a further breakdown of data?

From the August 2012 release onwards, accompanying the published tables, we have released underlying datasets that are used to produce the Population by country of birth and nationality tables. These datasets provide data on UK residents broken down by country of birth and nationality to a lower geographical level. This consists of UK regions, counties, London boroughs, metropolitan districts, unitary authorities and non-metropolitan districts. These data are often less accurate, but are accompanied by relevant footnotes to explain the limitations of the data.

Further breakdowns, by age for example, are not published on the website. To obtain these data please contact migstatsunit@ons.gov.uk providing details of the data you require; stating the variables, breakdowns, groupings, and time period, along with intended use. Providing this information will ensure that we are in the best position to deal with your request effectively.

More complex requests may incur a charge, but please contact migstatsunit@ons.gov.uk for further information about this.

5.4 The country I am looking for does not appear in the most common countries of birth and nationalities tables

As mentioned in Section 5.3, we now release underlying datasets that are used to produce the published tables, which will enable users to view data for most countries that do not appear in the most common countries of birth and nationality tables.

1. Population by Country of Birth and Nationality Tables

2. Underlying Datasheets to Accompany Population by Country of Birth Tables

3. Population by Country of Birth and Nationality Quality and Methodology Information

4. Local Area Migration Indicators Suite

5. 2011 Census webpage

6. 2011 Census data section

7. Detailed country of birth and nationality analysis from the 2011 Census of England and Wales

8. If you are new to migration statistics, you might find it helpful to read our Migration Statistics First Time User Guide, Glossary, and List of Products.