FOI reference: FOI-2025-3296
You asked
Under the Freedom of Information Act 2000, I would like to request the following information held by the Office for National Statistics regarding the resident population of Wales.
1. For each of the past five calendar years, please provide the number of foreign-born individuals residing in Wales, broken down (where data is held) by:
- British citizens born outside the UK
- Non-UK nationals with Indefinite Leave to Remain (ILR)
- Refugees / those granted humanitarian protection
- Asylum seekers
- Individuals with temporary or limited leave to remain (e.g. work, study, family visas)
- Persons with irregular, unresolved or unknown immigration status
- Individuals considered to be in Wales illegally
- Other categories used by ONS in published or unpublished datasets
2. For each category, please provide:
- Total estimated number of residents in Wales
- Any confidence intervals or methodological notes normally provided with such estimates
3. If ONS does not hold a full breakdown for certain categories, please provide:
- Any partial datasets you do hold
- Any linked administrative datasets used for population estimation
A list of datasets ONS considers relevant but are owned by other departments (e.g., Home Office)
ONS's official guidance on how immigration status is categorised for population-estimation purposes
4. If ONS cannot provide data for certain status groups due to responsibility resting with another department, please confirm:
Which department holds that data
Whether ONS receives any aggregated or derived data from them for Wales-level population estimates
We said
Thank you for your request.
We produce population estimates and related data primarily from the Census and survey sources. We do not hold detailed information on immigration status, visas, or legal categories such as Indefinite Leave to Remain, asylum seekers, or refugees.
Our best estimates of the population of Wales by country of birth are available from the Census 2021:
These represent two distinct populations captured in the Census 2021: usual residents and non-UK born short-term residents.
It is important to note when interpreting these estimates that some usual residents are born outside of the UK but are British. These can include individuals who temporarily lived in a foreign country, naval base, or were on holiday at the time of the birth. Individuals born outside of the UK can also hold more than one passport, such as a British passport and a passport from a different country.
We do not hold census data for the specific breakdowns you have requested in question 1. Where you have requested “other categories used by ONS in published or unpublished datasets”, further Census 2021 tables are available on Nomis, which can be explored to identify any other relevant data.
If you have any further queries regarding Census data, these can be directed to census.customer.services@ons.gov.uk.
Data on asylum seekers, refugees, visa holders, and irregular migrants is held by the Home Office. Their statistics on asylum, visas, and immigration status can be found here: Home Office Immigration System Statistics. They can be contacted at MigrationStatsEnquiries@homeoffice.gov.uk.
Historically, our non-UK born population estimates were based on the Annual Population Survey (APS). The publication of these APS-based estimates was discontinued in October 2022 due to an underlying data issue as a result of low survey response rates affecting the accuracy of the estimates produced.
We are reviewing the best methods to produce these estimates going forward, which includes exploring the quality of the APS as part of wider Labour Force Survey (LFS) improvements. We have continued to collect data on the non-UK born population, including the main reason for coming to the UK and right to work in the UK, to investigate and monitor the quality of these data as improvements are made to the LFS.
However, whilst these investigations continue, we do not recommend using APS data to understand the non-UK born population at this time.
If you would like to make a user request for these APS estimates, you can contact socialsurveys@ons.gov.uk outlining your data request. Please note that as well as the data issue outlined above, the sample for these questions in Wales will likely be low, and therefore suppression will be applied where appropriate. Responses to these questions are also provided by the respondents themselves, so they may not align with administrative figures, such as visa status records.
We may charge for this user request, in line with our charging policy. Charges can be made depending on the amount of time taken to develop the analyses and undertake quality and disclosure control processes. For more information on the services available, take a look at our publication scheme.
As this information is reasonably accessible via another route, even if only accessible on payment, Section 21(2)(a) of the Freedom of Information Act 2000 (FOIA) applies.