---
title: "Appendix E: Updated unauthorized immigrant population estimates for Europe and the United Kingdom, 2014-2017"
description: "Editorial note to readers (March 19, 2025): This project estimated the number of unauthorized immigrants living in 32 European countries during the mid- to late-2010s. We used what were then the best available data sources from different governments and from the European Union. After our report was published in November 2019, researchers at the University […]"
date: "2019-11-13"
authors:
  - name: "Phillip Connor"
    job_title: "Former Senior Researcher"
    link: "https://www.pewresearch.org/staff/phillip-connor/"
  - name: "Jeffrey S. Passel"
    job_title: "Senior Demographer"
    link: "https://www.pewresearch.org/staff/jeffrey-s-passel/"
url: "https://www.pewresearch.org/global/2019/11/13/eu-unauthorized-immigrants-appendix-e-updated-unauthorized-immigrant-population-estimates-for-europe-and-the-united-kingdom-2014-2017/"
categories:
  - "Immigrant Populations"
  - "Immigration & Migration"
  - "Unauthorized Immigration"
---

# Appendix E: Updated unauthorized immigrant population estimates for Europe and the United Kingdom, 2014-2017

**Editorial note to readers (March 19, 2025):**

This project estimated the number of unauthorized immigrants living in 32 European countries during the mid- to late-2010s. We used what were then the best available data sources from different governments and from the European Union. After our report was published in November 2019, researchers at the University of Oxford’s Migration Observatory [identified a problem](https://migrationobservatory.ox.ac.uk/resources/commentaries/recent-estimates-of-the-uks-irregular-migrant-population/) with the official data from the United Kingdom’s Office for National Statistics (ONS) on the number of legal immigrants residing in the UK.

The ONS data on legal immigrants that we used in our report did not include those with “indefinite leave to remain” (ILR), a group legally residing in the country. Including the ILR group among legal UK residents results in lower estimated total numbers of unauthorized immigrants for both the United Kingdom and Europe in 2017 and other years. The updated estimates for the number of unauthorized immigrants in 2017 (without waiting asylum seekers) are 700,000-900,000 for the UK and 2.8 million-3.5 million for Europe. [Updated estimates can be found in this table but are not reflected elsewhere in this report.](https://www.pewresearch.org/?p=202436&preview=1&_ppp=aa855f58a7)

[![](https://www.pewresearch.org/wp-content/uploads/sites/20/2025/03/RE_2025.03.18_Europe-unauthorized-immigrants_new.png)](https://www.pewresearch.org/?attachment_id=202437)