figure shows the personal income tax and overall tax wedge which also takes into account both social security contributions and transfers progression on average in the oecd at different income levels and for different family types looking at panel a progressivity is highest at the bottom of the income scale and declines with income for all family types tax wedge progressivity is generally lower than pit progressivity since the tax wedge includes social security contributions which are typically levied at a flat rate moreover tax wedge progression is lower than the average pit progression for families without children because the latter tend not to receive benefits which also tend to be targeted at low income levels this explains in part the higher rate of tax wedge progressivity than of personal income tax at low levels