Towards the Development of a Tax System Complexity Index

Abstract Reducing tax system complexity is a common goal amongst policymakers; yet there is no commonly agreed definition of complexity. This paper seeks to fill this gap, by proposing the construction of an index of tax system complexity, conceived as a summary indicator of the overall complexity of a tax system at a particular point in time. If adopted, such an index would not only enable assessment of the changing level of a country's tax system complexity over time, but may also facilitate comparisons of the relative complexity of different countries' tax systems in future.