This article examines the status quo of tax disclosure in the context of sustainability reporting and proposes recommendations for the creation of uniform EU Sustainability Reporting Standards. The analysis is based on the 2020 and 2021 sustainability reports of 112 firms listed in the three largest economies of the European Union: France, Germany and Italy. The authors have developed a multidimensional scoring model – the Tax Transparency Index – that considers both the extent and the manner of presentation of the textual information. The results show that the content coverage falls short of the requirements of the globally most widely applied tax sustainability reporting standard, GRI 207. Furthermore, it shows that tax sustainability reporting appears to be highly fragmented, making it difficult for users to find relevant information. Two implications emerge for the envisaged development of EU Sustainability Reporting Standards. First, a standardization of the materiality assessment and a limitation of the “comply-or-explain” principle with regard to taxes is needed. Second, the authors recommend disclosure of tax sustainability information within a single document and therefore welcome the recent mandate of the EU CSR Directive.