An individual is tax resident for a particular tax year if present in Ireland for 183 days or more in that year, or 280 days or more in that and the preceding year combined, including at least 30 days in each year. An individual is resident in Ireland for a day if present for any part of the day.
There are also specific tax rules in relation to split year relief which may have relevance to individuals arriving in or departing from Ireland.
'Ordinarily resident' is specifically defined under Irish tax law. An individual becomes 'ordinarily resident' after a continuous three consecutive year period of tax residence and lasts for a three-year period after normal tax residence has ceased.
'Domicile' is essentially the country which is considered to be an individual’s permanent home and is distinct from legal nationality and residence.