This report contains data on individuals detained in the Home Office detention estate and HM Prisons solely under Immigration Act powers. The detention estate comprises immigration removal centres (IRC) and short-term holding facilities (STHF).

The statistics in this report show the number of people leaving detention per year having been held solely under immigration powers. The statistics will include some individuals imprisoned in the UK following a criminal sentence, but only if subsequently detained under immigration powers. Some individuals may leave detention more than once in a year, and the statistics will include these people more than once.

This publication splits people in detention into three groups:
People detained within the UK following immigration offences: This includes (i) people who have overstayed their leave to remain in the UK; (ii) people who have breached the terms of their leave to remain (e.g. by working illegally); (iii) people who entered the country irregularly and are being returned to their home country or a safe third country; and (iv) people whose leave to remain has been curtailed.
Foreign national offenders (FNOs) in detention: This includes (i) FNOs transferred directly from prison to detention for return after completing a prison sentence; (ii) FNOs re-detained for return following release on bail; and (iii) people detained from the community for return following conviction for a crime overseas and considered a threat to the public.
People detained on arrival in the UK: This includes (i) people detained while attempting to enter the UK through a regular port of entry; and (ii) those apprehended attempting to enter the UK irregularly (or immediately after entering). These people were generally detained only for a short time (most for three days or less), and any issues raised by these people were generally being raised at the first opportunity in the UK. Therefore, this analysis does not include this group.