(Bloomberg) -- Irish unity would require large tax rises and cuts to public expenditure, according to a new study that lays bare the costs to the Republic of Ireland of any future reunification with Northern Ireland.

The cost to the economy of the Republic of Ireland would be around 5% of modified Gross National Income, according to the research from the Institute of International and European Affairs in Dublin. That could increase to 10% of GNI if Northern Ireland’s significantly lower welfare payments and public sector pay were brought in line with those in the republic, adding a quarter to public expenditure, it said. Ireland’s statistics office uses GNI as a more accurate measure of the Irish economy than GDP given the out-sized number of multinationals based there. 

“Even though Ireland has a much higher national income, funding the needs of the people of Northern Ireland in a united Ireland would put huge financial pressure on the people of Ireland, resulting in an immediate major reduction in their living standards,” said John FitzGerald, one of the report’s authors. 

Sinn Fein, which holds the most seats in the Northern Ireland Assembly and currently leads polls in the Republic, is campaigning to reunited Ireland. In March, the party’s leader, Mary Lou McDonald, said that a united Ireland is “within touching distance,” raising the prospect of a border poll, the mechanism to gauge backing for reunification set out in the 1998 Good Friday Agreement. that led to push-back from unionists in Northern Ireland who want to remain part of the UK. 

The report’s authors argued that the cost of reunification could be reduced “substantially” by making changes to the Northern Ireland economy addressing low productivity that currently makes it one of the poorest regions in the UK. However it would take “at least two decades before the productivity gap could be substantially narrowed,” the authors wrote. 

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