The Home Office is responsible for ordering detention of asylum applicants. There is no maximum period set in law, with the exception of detention of pregnant women and children which cannot exceed 72 hours, or 7 days with Ministerial approval. The Illegal Migration Act 2023 contains powers to detain children without a time limit, however these were never commenced and the Border Security, Asylum and Security Bill will repeal these provisions.
During 2025, 13,640 asylum applicants and 9,154 non-asylum applicants left immigration detention.[1] While data on length of immigration detention is available, the figures do not distinguish between asylum applicants and other immigration detainees. Periods of immigration detention including asylum applicants and other foreign nationals vary enormously from a few days to several years.
| Duration of stay in detention 2019 – 2024 | |||||||
| 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | |
| Less than one month | 18,076 | 11,968 | 21,074 | 14,150 | 11,539 | 13,437 | 15,442 |
| From one month to two months | 3,622 | 1,770 | 1,428 | 2,862 | 3,151 | 3,681 | 3,987 |
| From two to four months | 1,869 | 1,023 | 1,061 | 1,610 | 1,980 | 2,142 | 2,425 |
| From four months to 12 months | 849 | 641 | 710 | 735 | 1,004 | 1,065 | 864 |
| From one to two years | 122 | 100 | 79 | 72 | 118 | 85 | 69 |
| At least two years | 6 | 8 | 10 | 18 | 46 | 12 | 7 |
Source: Home Office, Immigration Statistics, Detention, table Det_D03.
The longest periods of detention are usually of people awaiting deportation after having served a criminal sentence.
[1] Home Office, ‘Immigration system statistics data tables, Immigration detention detailed datasets, year ending December 2025’, table Det_01, available here.