Using Fiscal Data to Estimate the Evolution of Top Income Shares in Belgium

Belgium is notoriously absent from the World Wealth and Income Database (http://wid.world/), the rapidly expanding international source of comparable data for research on income and wealth inequality. This paper reports on a first attempt to fill this gap. We correct and complete published data on net taxable incomes for the period 1990-2013 to comply with the standards set by the WID database, as expressed in the population control and the income control. Our results show that inferring evolutions of the income share of the top 10% or 1% from published tables of net taxable income is highly misleading. After correction, there is little evidence that top income shares in Belgium have increased during the last 25 years. In contrast to similar analyses for the UK, US, Germany, and to a lesser extent France and the Netherlands, we do not find a clear increase in the income share of the top decile. Also, the significant increase in the income share for the top one percent in many countries, cannot easily be replicated for Belgium. However, some caution is needed. The correction for missing income, preliminary though it is, points to the crucial role played by both our definition of the income reference total and of changing definitions and/or conventions in the National Accounts.