Tax is a fascinating policy space that brings together a mix of economic, social, legal, accounting and administrative policy issues, heavily overlaid with the political process. It is also contentious. A country’s tax system establishes how the burden of funding government services is shared in a community and changes to that are transparent. There is a lot at stake. The tax system has multiple objectives and policy inter-relationships. Tracing the history of tax theory illustrates how these considerations have been balanced by societies and their governments. Tax theory matters because consideration of tax reform requires a view of what the tax system should look like. The art of tax reform then, is about getting from where we are to where we want to be. The benchmark for the theoretically ideal tax system, though, has been much debated in the development of modern tax systems and this paper canvasses those issues.