Our fiscal deficit still soars over rest of UK - Business News, Business - Belfasttelegraph.co.uk
The linked news story explains that per capita there is a £6000 deficit in NI. That is, spending by government exceeds tax raised by £6000 per head.
Some basic maths - assuming the population of Ireland (Republic of) is double that of NI - indicates that a £3000 tax hike per head would be needed to sustain NI if there were to be a UI tomorrow. Politically unpalatable.
That is why we need to get economic development north of the border in order to make sure that a UI is not unattractive economically.
Hence the need for pro-growth policies that the Executive powersharing coalition is putting forward.