Adult Social Care Glossary, v 0.6

Leave is legal permission to be in the UK. Leave is granted by UKIV officers in accordance with the immigration rules, and may be recorded in a letter (these were phased out some years ago), a biometric residence card or a stamp in a passport. Any person who is subject to immigration control must have leave (or temporary admission) to lawfully enter or remain in the UK. Leave can be for a fixed period (limited leave) which can be granted with or without conditions (typically, no right to work or no public funds).

A person with leave can apply to have its period or conditions varied provided the application is made before the change occurs (i.e. before it has expired or before starting work/claiming public funds). Once leave has expired, a new application must be made.