Horizontal and vertical inequality in a social welfare framework

Resum

In this paper a new definition of horizontal inequality is adopted. It is defined in terms of the distributional change within intervals of similar households, produced by the Tax System. We believe that this definition is better suited for measurement of the comparative injustice that may be caused by the Tax System among similar households. In particular a within-group Atkinson inequality index applied to one minus the tax rates of similar households is proposed. It enables us to introduce this concept in a general social welfare framework together with efficiency and vertical equity redistribution considerations, where the horizontal equity and vertical redistribution are income-invariant measures. It contributes to a more appropriate evaluation of the desirability of tax reforms aimed at achieving greater horizontal equity.