Accredited official statistics

How many people are detained under immigration powers in the UK?

Published 22 May 2025

Back to ‘Immigration system statistics, year ending March 2025’ content page.

Data on detentions relates to the year ending March 2025 and all comparisons are with the year ending March 2024 (unless indicated otherwise).

An individual may be detained under immigration powers under certain circumstances. This includes detention in support of the return of the individual with no legal right to be in the UK. In some cases, individuals may be detained whilst their identity is being established or where there is a risk of absconding.

1. People entering immigration detention

The number of people entering detention increased in the year ending March 2025, continuing the recent upward trend since 2023.

A total of 20,919 people entered immigration detention in the year ending March 2025 under immigration powers, 10% higher than the previous year. This increase continues an upward trend seen since 2023 which followed a longer-term downward trend since 2015.

Figure 1: People entering immigration detention in the UK, rolling annual totals from 2015 to the year ending March 2025

Source: Immigration detention - Det_D01

Figure 1 shows the number of people entering detention reduced from around 32,400 people in 2015 to around 24,500 in 2019. The reduced use of immigration detention over this period can in part be linked to the Government’s response to the 2016 Stephen Shaw review of detention, which proposed a range of changes in the use of detention and greater use of alternatives.

While 2020 and 2021 were impacted by the COVID-19 pandemic, the general downward trend in the number of people entering detention continued up to the year ending September 2023. This reduction in part reflects the move to process small boat arrivals, on arrival at the Manston facility, outside of the detention estate – previously these arrivals entered the detention estate for a short period on arrival. The change has allowed more individuals to move directly to community-based accommodation, following the initial examination and checks, rather than be held in immigration detention, as was often the case up until early 2022.

The recent increase in numbers entering detention may in part reflect the use of detention to facilitate the increase in returns from the UK. The 10% increase in detention intake in the year ending March 2025 compared to the previous year coincides with a 20% rise in numbers of returns from detention (see ‘How many people are returned from the UK?’ for more information). In addition, the proportion of individuals leaving detention in order to be returned to a country outside the UK has increased from 41% to 44% over the same period.

Albanians were the most common nationality entering detention in the year ending March 2025.

In the year ending March 2025, there were 5,603 cases of Albanians entering detention, accounting for more than a quarter (27%) of total entries. However, since 2022, the number of Albanians entering detention annually has been falling, and in the latest year was 28% lower than the peak of 7,861 entering in the year ending March 2023. This decrease mirrors the sharp fall in Albanian small boat arrivals over the same period.

There has been a rise in the number of Brazilians (up 63%), Indians (up 45%) and Romanians (up 31%), these were the second, third and fourth most common nationalities entering detention during the latest year.

2. People in immigration detention

The number of people being held under immigration powers in the UK was slightly lower on 31st March 2025 compared with a year prior.

There were 1,806 people being held in detention (at an immigration detention facility or in prisons under immigration powers) at the end of March 2025, which is 6% lower than one year earlier.

Figure 2 shows that while there has been relative stability in numbers held in detention in recent years, this contrasts with preceding years. Numbers decreased sharply at the start of the COVID-19 pandemic, and fluctuated greatly during 2022 and 2023. They have since stabilised at levels similar to those seen just prior to the pandemic.

The vast majority of people detained under Immigration powers are detained in the immigration detention estate rather than prisons. On 31 March 2025 there were just 93 foreign national offenders (FNOs) detained in prisons under immigration powers and this number has been around 100 since the second half of 2023. Around this time, some FNOs who had served their custodial sentence in prison started being transferred into the immigration detention estate if assessed as suitable and low risk, helping to address prison capacity constraints. Prior to this, the number of people detained in the prison estate has been typically much higher, ranging between 300 and 700 in the period from late 2017 to mid 2023.

The total number of foreign nationals held in prison for criminal offences can be found in the latest prison population statistics, published by the Ministry of Justice and HM Prison and Probation Service.

Figure 2: People detained under immigration powers in the UK, on the last day of the quarter, 31 March 2018 to 31 March 2025¹

Source: Immigration detention - Det_D02

Notes:

1. The ‘detention estate’ comprises Immigration Removal Centres (IRC), Short-Term Holding Facilities (STHF) and Pre-departure Accommodation (PDA). It is separate to those who are detained under immigration powers in prisons – these are shown separately on the chart.

The number of people in detention is a snapshot relating to a single point in time, therefore, numbers fluctuate daily. If a large number of people entered detention just before the end of a reporting period, the number of people in detention would be higher than if the same people entered a few days later.

3. People leaving immigration detention

Lengths of detention for individuals leaving immigration detention in the year ending March 2025 were similar to the previous year with just over a third detained for between one week and a month and just over a quarter detained for one week or less.

Figure 3 shows that from 2010 to 2019, prior to the rise in small boat arrivals, the most common length of detention for people leaving immigration detention was one week or less (37% of leavers), largely due to detention’s primary use in preparing people for return from the UK. However, over the last 2 years the most common length of detention has been over one week to less than one month (38% of leavers). The proportion of people detained for long periods; however, (one month and over) has remained similar since 2010, excluding 2021 and 2022 where shorter stays became very common due to pandemic restrictions, and the processing of small boat arrivals within the detention estate.

Since the start of 2022, small boat arrivals are no longer being processed within the detention estate, and detention is again mainly used to prepare people for removal. There is more information below on reasons for people leaving detention.

Figure 3: People leaving immigration detention, by length of detention^1,2, proportions of rolling annual totals, from 2010 to the year ending March 2025

Source: Immigration detention - Det_D03

Notes:

1. ’<’ means ‘less than’.
2. Month duration refers to a period of 30 days.

The most common reason for leaving detention in the year ending March 2025 was bail.

Figure 4 shows that the number of individuals leaving detention on immigration bail in the latest year (10,697 or 51% of leavers) is slightly higher than the number being removed from the UK upon leaving detention (9,190 or 44%). There has been a near tripling in the number of returns from detention, combined with a 50% fall in numbers of detained individuals leaving on bail, since the year ending March 2022.

Figure 4: People leaving detention by reason for leaving^1,2,3 from 2010 to the year ending March 2025

Source: Immigration detention - Det_D03

Notes:

1. Bailed Secretary of State (SoS) and Immigration Judge (IJ).
2. Other reasons for leaving detention include being sectioned under the Mental Health Act, entering criminal detention, being granted leave to enter (LTE) or remain (LTR) in the UK, being detained in error and people whose reason for leaving was not available at the time of publication. See the user guide for more details.
3. The legend follows the same order and orientation as the stacks within the chart.

The proportion of people leaving detention to be returned from the UK is now at levels similar to those seen in 2019.

Albanian nationals were the most common nationality being returned from detention in the year ending March 2025 (27% of all leavers being returned), as they were the previous year (37%). The large number of Albanians being returned has followed the agreement between the UK and Albanian governments, the UK-Albania Joint Communique to deter and disrupt illegal migration and criminal networks, which was signed at the end of 2022.

The increase in numbers of returns from detention over the last few years contrasts with a longer term fall that can in part be linked to increasing numbers of detained individuals raising issues that have prevented their return, as described in the Home Office research paper ‘Issues raised by people facing return in immigration detention’ (2021). This research showed that 73% of people detained within the UK following immigration offences in 2019 were recorded as having raised one or more issues that may have delayed or prevented their return. These issues included raising an asylum claim, making a legal challenge, or a claim to be a potential victim of modern slavery or human trafficking.

Further information on the number of people returned can be found in ‘How many people are returned from the UK?’ chapter of the Immigration system statistics quarterly release. Numbers of people being returned from Pre-Departure Accommodation (PDAs) are published in the quarterly Immigration Enforcement Transparency data tables.

As outlined in the intention to publish statement released by the Home Office in April, following upgrades to FNO data collection and infrastructure currently underway, the Home Office proposes to publish further statistics on FNOs in the immigration system later this year.

4. About the statistics

The statistics in this section relate to detention under immigration powers.

One individual may enter or leave detention multiple times in a given period and will therefore have been counted multiple times in the statistics.

5. Data tables

Data referred to here can be found in the following tables:

• Immigration detention summary tables
• Detailed immigration detention datasets

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