Ireland is more lenient than the UK in that respect, indeed it is 183 days. Depending on when you leave the country that could be a big advantage, e.g. I went expat in April several years ago, and got all my tax back for that year within a few weeks, once I informed them that I was leaving the country and therefore would not hit the 183 days in the country. Also, even if you arrive back in the country mid way through the year, you still get the full tax allowances for the year, so can pay minimal income tax at the higher rate.