What is ordinary residence?
You are regarded as ordinarily resident in the Republic of Ireland (ROI) if you have been ROI resident in each of the three immediately preceding tax years. If you are non-resident in Ireland but you are ordinarily resident, you are taxed as if you were resident, but you are not subject to Irish tax in respect of income from a trade, profession, or employment carried on outside Ireland. However, you are liable in respect of investment income in excess of €3,810 arising outside Ireland.
You cease to be ordinarily resident when you have become non-resident for the three immediately preceding tax years.
Ordinary residence is important if you have substantial investment income and you go to work abroad for a temporary period. You remain liable to Irish income tax on the investment income, even though you are living abroad.