What is domicile?
Domicile is a concept of general law. It broadly means living in a country with the intention of living there permanently. Domicile is a much more permanent concept than residence.
Everyone has a 'domicile of origin' at birth, usually the domicile of the father. You keep your domicile of origin unless you choose to gain a new domicile.
To gain a new domicile, you must show clear evidence that you intend to live permanently in the new country and you do not intend to return to live in your domicile of origin. For example, if you have an Irish domicile of origin, you live abroad for a number of years and you return to Ireland, you are not regarded as losing your Irish domicile of origin.
Your domicile affects how foreign-source income is taxed in Ireland.
Next: Tax treaties between Ireland and other countries