PRESS STATEMENT
Country-Level Revenue Estimates – A Comparative Analysis of UN and OECD Subject to Tax Rules for 65 Member States of the G-24 and South Centre
Washington and Geneva, 23 July 2025
The South Centre & Group of Twenty-four today jointly released country-level revenue estimates of the UN & OECD Subject to Tax Rule (STTR) for their 65 combined Member States.
Results show higher revenues from UN STTR, and reinforce benefits of a UN Tax Convention.
Comparison of Tax Revenue Effects of United Nations and OECD Subject to Tax Rule for G-24 and South Centre Member States
By Faith Amaro and Sol Picciotto
The Subject to Tax Rule (STTR) seeks to address the historical imbalance in the allocation of taxing rights under international tax treaties by introducing within existing treaties a new article which makes the restrictions on source taxation conditional on the residence jurisdiction imposing a minimum level of tax on foreign-derived income. This paper presents a methodology for analysing the respective benefits of the STTRs developed by the Organisation of Economic Co-operation and Development (OECD) and the United Nations (UN). Applying this model to publicly available data for 2021, it also provides estimates of the possible revenue impact for the 65 Member States of the South Centre (SC) and the Intergovernmental Group of 24 (G-24). Our analysis indicates that the OECD STTR would have no impact on any OECD country treaty with a SC/G-24 Member State. Applying the prescribed 9% minimum rate to covered payments, only 100 treaties across 28 SC/G-24 Member States would qualify for improvement under the OECD STTR, with an estimated combined revenue gain of USD 55.6 million, 71% of which is concentrated in just five treaties. In contrast, the UN STTR, which does not specify a minimum rate, was modelled using rates of 9%, 10% and 15%. This resulted in estimated revenue gains of USD 212 million, USD 325 million, and USD 1,165 million across 171, 210 and 317 treaties, respectively. Given its complexity and restrictive scope, it seems pointless for any SC/G-24 Member State to join the OECD STTR. Instead, countries should focus on identifying treaties that cause unjustifiable revenue losses and consider revising them – either by adopting the simpler and broader UN STTR or implementing other measures such as active anti-abuse provisions to combat treaty shopping and tax avoidance.
Analysing the Impact of UN and OECD Subject to Tax Rule for G-24 and South Centre Member States
By Suranjali Tandon and Chetan Rao
The Subject to Tax Rule (STTR) is meant to address base erosion and profit shifting in cross –border transactions. The United Nations (UN) and Organisation for Economic Co-operation and Development (OECD)/Group of Twenty (G20) Inclusive Framework have developed models of the STTR that countries may choose to adopt in their treaties. This paper provides a review of these designs of two STTR models and proceeds to estimate the revenue gains for the Intergovernmental Group of Twenty-Four on International Monetary Affairs and Development (G-24) and South Centre Member States that may arise from a STTR that covers different kinds of payments. The OECD STTR is limited to related-party payments and imposes thresholds based on mark-up and materiality, reducing its applicability in practice. In contrast, the UN STTR offers broader coverage, applies to both related and unrelated parties, and does not impose restrictive thresholds, making it more administratively feasible for developing countries. Although the estimated gains from the OECD STTR appear modest due to its narrow scope, the UN STTR shows greater potential. The analysis also highlights data limitations and the need for access to microdata for accurate country-level assessments.
