UK or the Eurozone: Which Common Currency Area Can Work for Northern Ireland After Brexit?

Brexit and the controversy concerning an Irish border makes the issue of whether Northern Ireland is a common currency area with the rest of UK or the Eurozone topical. We test the microeconomic foundations of a common currency area for Northern Ireland, UK, Great Britain and Northern Ireland in the Eurozone. We provide evidence that all areas meet the microeconomic criteria for a common currency area. Banking data suggest that lending in Northern Ireland is different from lending in the rest of the UK, raising doubt on whether or not the UK forms a common currency area including Northern Ireland.