Estimating the budgetary impulse of a top wealth tax before macroeconomic effects

In the context of the election programme costing exercise, the Federal Planning Bureau is anticipating proposals from political parties for the introduction of a top wealth tax. The purpose of this document is to explain the estimation method for its budgetary impulse. To do so, we use data from the Belgian National Bank's Household Financial Behaviour Survey. We develop the calculation method for estimating revenues with or without the potential behavioural responses of taxpayers. To include potential behavioural responses, we investigate two approaches, namely the bunching method and the inclusion of net wealth elasticities estimated abroad. Based on the results, we will preserve only the second method for the DC2024 costing. Furthermore, this paper reviews the literature on the macroeconomic effects of the top wealth tax - literature relevant to understand the inclusion of the tax in the HERMES and QUEST models.