It maybe exempt, if its income earned and taxed abroad whilst you were non resident and not liable to tax in Ireland then I would not have thought bringing it back would attract taxes, and if it did then I would assume it would be income rather than capital gains.
When did you earn it, when did you return to Ireland that's what you have to look at, as many people have worked abroad saved money on their earnings and then came to Ireland and brought in without being liable to irish tax.
If its a large amount, then maybe seek tax advice, but look at revenue website to see how monies earned abroad whilst not liable to irish tax is treated.
I assume you would need to disclose on your tax return as its a foreign asset, but just spending this maynot have any tax liability, and if not liable to income tax then I'd say no gain/loss allowed for CGT.