Northern Ireland vs Republic of Ireland Income Tax (2025/26)

Regardless of which country you work in, enter in GBP. The calculator converts to EUR for ROI calculations.

Default is BoE 30-day average. For today's rate check xe.com. If you're banking cross-border, add 1% for realistic retail rate.

Single, married one-earner, or married two-earner. Only affects ROI bands; UK treats each spouse independently.

ROI-specific €1,950 credit if one spouse stays home with a dependent. Only enabled for married-one-earner.

Applied to UK side only. ROI pension reliefs differ and are not modelled — use Revenue.ie MyAccount for that.

Nominal differences are one thing; cost-of-living adjusted differences often flip the winner.

Signed 1976, most recently amended 2016. The DTA prevents you being taxed twice on the same income. Key principles: (1) employment income is taxed where the work is physically done (source state), (2) the residence state grants credit for tax paid in the source state, (3) tie-breaker rules apply for dual residents. For NI residents working in ROI, the Frontier Workers Relief (Revenue TDM 34-00-08) allows ROI-source income to be taxed at UK effective rates — a significant benefit at mid-income levels.

Since the EU/UK Social Security Protocol (part of the Trade and Cooperation Agreement 2021), PRSI contributions in ROI and NI contributions in UK are treated as aggregating for pension eligibility. Cross-border workers accumulate credits in both systems proportional to where they work. This means a 10-year NI commuter to Dundalk accumulates pension credits in both UK State Pension and Irish Contributory Pension — often receiving partial amounts from both. HMRC NI38 and DSP guidance apply.

ROI allows married couples to transfer up to €36,800 of unused standard rate band between spouses (for 2025). This means a dual-income couple with wildly uneven earnings (e.g. one on €80k, one on €20k) can share the band more efficiently: the €80k earner uses €80k at 20% instead of €44k at 20% + €36k at 40%. For UK couples, equivalent optimisation is via pension contributions — not band transfers. This makes ROI significantly more progressive for uneven-earner households.

At income above €70,044 and without medical card reductions, the ROI marginal rate is 40% (income tax) + 8% (USC) + 4.1% (PRSI) = 52.1%. This is among the highest in Western Europe, rivalling Belgium and France. By contrast, UK 45% Additional rate + 2% NI = 47% — lower until you hit the £100k-£125,140 Personal Allowance taper where UK spikes to ~62%. High earners generally prefer UK until £200k+ where ROI's lack of PA taper becomes an advantage.

Numbeo Feb 2026 indices (UK avg = 100): Belfast 88, Derry 82, Dublin 118, Cork 99, Galway 96, Letterkenny 76, Dundalk 88. Housing accounts for most of the variance — Dublin rent is 2.1× Belfast for equivalent properties. A €45k Dublin salary has equivalent purchasing power to £30k Belfast salary after COL. For ROI cross-border commuters living in NI, the best of both worlds: ROI-level nominal pay (40%+ of roles pay €40k+) with NI-level cost base.