The term ‘non-dom’ is applied to a UK resident who has a foreign (non-UK) ‘domicile’.
A person’s domicile is generally the place they consider their permanent home, the place with which they have the strongest social and family ties. Unlike residence, there is no one legal test to determine domicile, but various factors are considered. Determining legal domicile can be complex, and it is open to challenge by HMRC, so advice should be taken.
While it is possible to be resident in more than one place at any one time, it is only possible to be domiciled in one jurisdiction.
Someone who has moved to the UK for a short period of time is likely to be a non-dom. People who have lived here for many years may also retain a foreign domicile if they intend to leave the UK at a foreseeable time or on a foreseeable event occurring.