Originally posted on Business Post 05 December 2021.

We need more information on the opportunities and challenges that a 32-county regime would bring for businesses as well as individuals

The Red C opinion poll in this newspaper last week highlighted the jarring reality that while many of us might aspire to the notion of a united Ireland, our views might change dramatically if it comes to paying for it.

There is precedent for this reaction. The most prominent reunification in recent memory was that of East and West Germany. To fund that particular initiative, a solidarity surcharge was introduced which put a few additional percentage points on most existing taxes.

The levy still exists today in many cases and suggests a solidarity surcharge may need to feature in debates over a united Ireland too. The travails of the Irish economy and the levels of indebtedness are well known, but the private sector is thriving. By contrast, the Northern Ireland economy is unbalanced.

The proportion of public-sector to private-sector activity in Northern Ireland is considerably higher than usual – 27 per cent of workers in Northern Ireland are employed in the public sector. In the Republic, the Department of Public Expenditure and Reform reports 350,000 public sector jobs, suggesting that only 14 per cent of workers in the South are paid out of public funds.

In terms of tax collected, Northern Ireland typically accounts for approximately 2 per cent of all British tax receipts, or just over £15 billion (€17.6 billion). The Revenue Commissioners in the South will collect something in the order of €90 billion in gross receipts this year.

A block grant is paid from Westminster to bridge the gap between what taxpayers in Northern Ireland pay and the cost of providing all the jobs and public services in the region. This subvention runs at the rate of approximately £1 billion a month, a British funding hydrant that would surely dwindle, if not get turned off entirely, in the event of unification.

The political players in Northern Ireland are wedded to their Westminster block grant, as is shown in their approach to how Northern Ireland companies are taxed. Stormont has had the power to set its own corporation tax rate since 2015, but adjusting the rate would come at the cost of reducing the block grant subvention from Westminster, so it hasn’t happened.

We need some better perspective on the opportunities and the challenges that businesses, and not just individuals, would have within a putative 32-county regime.

A united Ireland will surely mean some move towards harmonised income and corporation tax rates across the island, if only because Brussels would insist on it as a condition of re-admitting Northern Ireland to the EU. A harmonised corporation tax rate might be unlikely to rest at 12.5 per cent for most industry, but the all-island rate could be lower than the 19 per cent rate currently paid in Northern Ireland and which is due to increase for larger businesses to 25 per cent from 2023.

Businesses would also need to factor in the costs of employment under a harmonised income tax and national insurance regime. According to recent OECD comparisons, the typical tax cost of employing a person on the average wage is remarkably similar North and South of the border.

While the tax wedge – PAYE and National Insurance or PRSI combined – is around 31 per cent on average in both jurisdictions, this can change dramatically depending on family circumstances and different wage rates. Tax considerations aside, government and employers alike would have to wrestle with the significant differences in labour law which currently exist on the island.

One of the biggest challenges for a truly all-island economy could come from losing Northern Ireland's privileged trade status under the Northern Ireland protocol. Despite the wrinkles in the protocol (and I do not discount the practical difficulties in its operation), the opportunity now available to Northern Ireland business to sell goods into both the EU and British markets without hindrance is a unique benefit. Neither the EU nor Britain would see any advantage in allowing one EU member country or region of the remaining 27 countries to have any form of privileged access to their respective markets.

While undoubtedly there would be transitional arrangements and sunset clauses established were the political accommodation ever to come to pass, these could not be prolonged indefinitely. It is not only individuals that might be asked to pay more tax in a united Ireland; businesses in both the North and South would have to as well. Some form of solidarity surcharge would be an unavoidable consequence.

Brexit has shown us what can happen when political decisions on sovereignty are taken without care for the legitimate concerns of industry. If the concerns of business are left out of the debate about a united Ireland, everyone will be worse off.

Dr Brian Keegan is Director of Public Policy at Chartered Accountants Ireland