If it's a pre-2008 car and on the old engine capacity based tax system, then it'll be €514 for a year's tax. If it's post-2008 and on the current CO2-based tax system then it will depend on the emissions, but you can find a full breakdown of the rates here: http://www.carzone.ie/news/motoringadvice/Motor-and-Road-Tax-Prices-Ireland-2016-1437.html