I would like to thank Duke for once again being part of my local-bottom indicator, picked up some MSTR at open that are already trading over 20% higher.
Assuming you are Irish and have been here for a long time, you will not lose your status as ordinarily resident for tax purposes, for 3+ years after you leave the State.
So an Irish-domiciled individual will be liable for CGT on worldwide gains during the year of leaving Ireland and for the following three tax years.
You may have a measure of relief under a DTA, but if the whole purpose of the exercise was to go somewhere that doesn't tax the gain, then DTA relief is irrelevant.