High Net Worth Individuals (HNWIs) pose significant challenges to tax administrations due to the complexity of their affairs, their revenue contribution, the opportunity for aggressive tax planning, and the impact of their compliance behaviour on the integrity of the tax system. This publication examines in detail this taxpayer segment, describes their usage of aggressive tax planning schemes and proposes prevention, detection and response strategies that tax administrations can use to respond to these challenges. It also addresses aspects of voluntary disclosure initiatives for past non-compliance that may be particularly pertinent in the current environment. The publication outlines a number of innovative approaches to enable governments to better manage the risks involved with marketed tax schemes and tailor-made arrangements. To improve compliance, tax administrations could consider changing the structure of their operations to focus resources effectively, for example, through the creation of a dedicated HNWI unit. Other recommendations include creating the appropriate legal framework, exploring forms of co-operative compliance and engaging more in international co-operation, at both the strategic and operational level.