The increasing similarity of Income Tax and National Insurance highlights the potential benefits of amalgamating them: transparency and administrative efficiency. No previous research has fully explored this possibility, and successive governments have argued that it is too problematic to pursue. However, with the present government talking about tax simplification, and both main opposition parties undertaking radical reviews of their tax policies, there may well be a greater willingness to consider reform in this area than in the past. This research will provide the first full examination of the issues that integration would raise and how any difficulties might be overcome, taking an interdisciplinary approach to look at both the technical obstacles to integration and the wider public policy issues. The research is being carried out in conjunction with Glen Loutzenhiser of the University of Oxford.