This article, which builds on an earlier one by the same authors, aims to make a further step in the definition of the fundamental elements of a blockchain-based tax system by developing a comprehensive theoretical framework for the use of blockchain technology in the tax domain. Based on literature review and conceptual legal analysis, the authors zoom in on three building blocks respectively focusing on the governance, legal and technology aspects. Each building block is composed of a series of conceptual items that require the attention of legislators, founding entities and developers while starting to approach the design of a blockchain solution for tax. In the authors’ view, only by first solving the issues related to each of these items in a coordinated manner will it be finally possible to enable governments and tax authorities across the globe to promote a gradual shift towards a blockchain-based tax system.