The report has been prepared in the framework of the Platform for Collaboration on Tax (the “PCT”), under the responsibility of the Secretariats and Staff of the four mandated organizations. The report reflects a broad consensus among these staff, but should not be regarded as the officially endorsed views of those organizations or of their member countries. The request arises in the context of increased recognition of the centrality to development of strong tax systems and of the importance of external support in building them, and a correspondingly increased willingness of advanced economies to provide substantially greater financing and other support for this. It recognizes that, while real progress has been made on increasing tax revenues in low income countries over the past two decades, for many countries revenues remain well below levels that are likely needed to achieve the 2030 Sustainable Development Goals, and to secure robust and stable growth. The report also takes as a fundamental premise that it is not just how much revenue is raised that matters for development and growth, but also how it is raised—and that strong tax systems are key for both equity objectives and enhancing state building.