To date, legislators and policymakers have not yet used any explicit policy criterion to balance transparency matters when dealing with EU and OECD tax dispute resolution reforms. This article wants to fill this void by providing a unique tool for implementing changes in international tax dispute resolution mechanisms, balancing different expectations and needs of stakeholders. Providing an example of its application, it proposes the use of differentiated levels of transparency according to stakeholders’ interests to ensure efficiency and fairness of outcome. The article employs principles of data protection regulations as a means to propose changes, drawing inspiration from comparable dispute resolution regimes that deal with taxation matters (Investor-State Dispute Settlement, International Commercial Arbitration and World Trade Organization dispute resolution mechanism). It concludes by providing proposals to render more efficient the current EU and OECD tax dispute resolution mechanisms.