In UK tax law, the beneficial ownership concept is an important method of attribution which connects a res to an owner for the purposes of tax law. The title of this thesis may be broken down into four components: 1) beneficial ownership; 2) attribution; 3) res; and 4) UK tax law. This thesis will therefore explore what beneficial ownership is, how it performs its main function of attributing a res to a person, what a res is and what other rights may be attributed, and how the above applies within the confines of UK tax law. This thesis briefly discusses related (but distinct) concepts of beneficial ownership in other areas of tax law but focuses on the concept as it applies in the context of what it refers to as ‘UK domestic tax law’. Beneficial ownership is part of a group of related concepts (referred to collectively in this thesis as ‘combined subdivision variants’) which largely serve a similar purpose and are often interchangeably used. More broadly, beneficial ownership is one of several methods of attribution used in UK tax law to connect a res (or, more broadly, an asset) to a person for various tax purposes. This thesis considers the distinctiveness of the beneficial ownership concept and how it fits within this broad taxonomy of methods of attribution. Four main research questions have been framed and answered by this thesis: 1) why is it important to attribute assets (and res) to persons under UK tax law; 2) what are the methods of attribution (especially beneficial ownership) and how are they used in UK tax law; 3) how can the methods of attribution be used in legislative drafting to achieve tax policy goals; and 4) how might a framework for using methods of attribution to achieve drafting goals be developed?