Digital Government and SDG 9 in the European Union: Institutional Saturation, Digital Co-Investment, and the EU15/EU13 Divide

Digital government is widely regarded as a catalyst for sustainable development, yet the mechanisms by which e-government adoption translates into progress on the SDGs remain poorly understood, particularly in high-income contexts where governance is already mature. This study addresses that gap using a balanced panel of all 27 EU member states over 2015–2023. Applying two-way fixed-effects estimation with formal Baron–Kenny mediation and country-block bootstrap inference, we identify three findings that collectively reframe the relationship between digital government and sustainable development in the European context. First, the widely assumed governance reform pathway is not empirically supported in the EU27: e-government adoption is not associated with measurable improvement in institutional quality, consistent with structural saturation rather than policy failure. Second, the benefits of digital government are unevenly distributed across the EU: old member states (EU15) exhibit significant positive effects on SDG 9: Innovation and Infrastructure, whereas new member states (EU13) do not, challenging the assumption that digital strategies yield symmetric returns across the Union. Third, and most importantly, the EU15 effect appears to be fully channelled through household internet access, consistent with a digital co-investment mechanism in which e-government uptake and broadband infrastructure co-evolve as expressions of a shared national digital transformation strategy. These findings inform the policy debate: the question for EU15 is not whether to invest in e-government, but how to sustain the joint infrastructure investment that makes it effective; for EU13, the priority is to establish the digital and institutional foundations that enable the mechanism to be activated.