Lucía Contreras, Felix Hugger & Tom Zawisza, MNE Responses to the Global Minimum Tax, OECD Tax’n Working Papers No. 77 (2026):
The Global Minimum Tax (GMT), implemented in 2024, represents a significant change in the international tax system. This paper uses a difference-in-differences framework to assess the short-term impact of the GMT, including on effective tax rates, investment and employment. Based on group-level Orbis data, the analysis finds that in the first year after the introduction of the GMT, relatively low-taxed MNEs experienced
a statistically significant increase in their effective tax rates of 1.7 percentage points. The increase for all firms is 1.4 percentage points. However, this increase was not accompanied by a reduction in investment or employment. The analysis indicates no anticipatory responses. Heterogeneity analyses suggest that the effects on effective tax rates are driven by MNEs which were more likely to have engaged in tax planning and MNEs with higher profit-to-substance ratios. The point estimates in terms of ETRs suggest that the GMT resulted in an increase of EUR 79bn-109bn in tax revenue globally in the first year of its implementation, equivalent to 2.4-3.4% of global corporate income tax revenue.
From the conclusion:
The analysis conducted can help to inform future international tax policy and continuing analysis of the GMT. At the same time and given the limited data available on the post-implementation period, the results represent short-run effects. MNEs might adjust their behaviour only gradually over time. The reduction of the substance exclusion over the coming years set out in the GloBE rules and the full entry into force of the UTPR might also induce the effects of the GMT to become stronger over time as the share of MNE profits under the GMT rises further. The implementation of the Side-by-Side agreement of 2026 and other recent changes could also impact the effects of the GMT in some jurisdictions. Future analysis based on additional years of data will be necessary to complement the findings presented in this paper with a longer-run perspective. Additionally, the paper finds that in-scope MNEs did not change their total investment in response to the GMT. These findings could be due to the design of the GMT and its substance carve-out which implies no change in the taxation of profits stemming from substance-heavy activities, or the effective targeting of the GMT on profit shifting activities which is less likely to impact the returns on marginal investments. Alternatively, the effects of investment and employment could be too small to be identified using the approach in this paper. It is also possible that while MNEs did not respond in terms of total investment, they have responded with a reshuffling of activities across jurisdictions. Analysis using jurisdiction-level data will be important to determine the extent of such responses.
