Debt—The First 100 Years: Fiscal Sustainability in Ireland 1924–2023

ABSTRACT This paper assesses the sustainability of Ireland's public debt to modified gross national income ratio since 1924 using a smooth transition autoregressive model. Empirical findings show that Ireland's debt has historically been mean reverting, exhibiting both non‐linear and asymmetric behaviour. The speed of adjustment was highest during two brief periods, centred around 1990 and 2016, characterised by simultaneous growth in nominal income and reductions in public debt.