"The complexity of tax law, like the complexity of the commercial world to which it applies, often seems to increase in an exponential fashion, placing ever more pressure on taxpayers, tax advisers and tax administrators. The problems are compounded many times by the inevitable shift of tax administration towards self-assessment models in which taxpayers have primary responsibility for correctly reporting information to the tax authority and face penalties for incorrect or incomplete reporting. This, in turn, requires taxpayers to rely increasingly on advice by tax authorities and, as a consequence, requires tax authorities to articulate their view of the law publicly. In some cases, where relevant statutory authority, case law precedents (where used) or interpretation doctrines are clear, this process is purely one of interpretation. In other cases, the basis for interpretation is less certain and the interpretation function leaves more room for discretion by the tax authority. Finally, in other cases, the legislature may delegate discretionary powers to the tax administration which effectively result in the authorities having a power to make law. This delegation may be bestowed expressly or implicitly, the latter by ignoring cases where the tax administration fills in gaps in the legislation using its own views. Such instances of discretionary law making powers arising explicitly or implicitly sit beside regimes that explicitly delegate to the executive the power to make law in selected areas by way of regulation. The extension of discretionary powers to make law to the executive, and in particular the tax administration, raises important questions about the delicate balance between the need to provide the executive and administration with sufficient room to apply the law and the need to maintain the principle of the rule of law that it is the elected legislature, and not the executive or tax administration, that establishes tax burdens. The chapters in this volume explore that delicate balance. These chapters derive from a project sponsored by the Oxford University Centre for Business Taxation (OUCBT) together with the Department of Business Law and Taxation at Monash University and the Australian School of Taxation and Business Law, University of New South Wales."--Preface.