IHTM13027 - Change of Domicile: Membership of Armed Forces
From 6 April 2025, for inheritance tax purposes, domicile is replaced by long-term UK residence and you can find details of these rules at IHTM47000.
A person who spends a period of duty in the UK solely because they are a member of a visiting force is not treated as resident in the UK for Inheritance Tax purposes. Neither does such a tour of duty affect domicile (to 5 April 2025) nor long term UK residence (from 6 April 2025) as long as the person is not a British citizen (IHTA84/S155 (2)). This includes civilians attached to any such force.
However, you should bear in mind that someone on a tour of duty could change their domicile prior to 6 April 2025, if they decide to remain permanently or indefinitely in the UK. All the relevant facts should be considered.
For further information on IHTA84/S155 see IHTM04321.