Despite growing commitments to international tax cooperation from the G20 and Global South (GS) partners, a persistent imbalance in fiscal capacity, bargaining power, and policy priorities leaves GS countries vulnerable to tax deals that limit revenue generation and economic sovereignty. The UN has emphasised the need for a more equitable international tax system, particularly as the OECD-led model fails to account for the specific needs of GS economies, creating avenues for avoidance and poor revenue performance. This policy brief presents a case for the development of a UN-centred framework that redefines global tax coordination by prioritising inclusivity, progressivity, and revenue strategies that foster sustainable development. The policy brief addresses two key barriers to fair international taxation: 1) tax avoidance and evasion due to unfavourable agreements and 2) failures of current international tax regimes to address development goals. To counter these issues, we propose four actions G20 members can take to champion international tax cooperation to meet development goals.