Revenue-maximising tax rates and elasticities of taxable income inNew Zealand

Abstract

The empirical literature on the elasticity of taxable income (ETI) sometimes questions whether estimated values are consistent with being on the revenue-increasing section of the Laffer curve, usually in the context of a single rate tax system or for top marginal rates. This paper obtains expressions for this ‘Laffer-maximum’ or revenue-maximising ETI which can be applied to any tax rate in a multi-rate system. For the New Zealand income tax system in 2010, it is found that a wide range of revenue-maximising ETI values can be expected across individual taxpayers, across tax brackets and in aggregate. The paper also simulates the effect of multi-rate tax reforms on these revenue-maximising ETIs.