This article updates earlier work on the scale of the UK ‘subvention’ to Northern Ireland. It deconstructs the largest elements of the subvention, analysing the likely impact of each in the context of unity. It calculates that the most likely outcome is an inherited deficit of £1.5bn per annum, with additional costs in equalising public sector wages, state pensions and benefits, which are much higher in the Republic. The article assumes that public expenditure would increase by at least €1bn p.a. to boost economic performance and to deal with crises in public services including health. Three growth scenarios are explored, reflecting experience in central Europe after states joined the EU. The analysis suggests that Northern Ireland’s public finances would reach [End Page 130]break-even between five and fourteen years after unity—making the cost affordable for the existing Republic through use of the state’s sovereign fund, or by borrowing for the transition period.