The aim of a welfare state is to allow provide access to vital services for all, but especially for those who could not otherwise afford them -to lift the burden of poverty somewhat. A flat tax, however, would actually increase the burden on the poorest. [1] For example, if under a progressive taxation system the highest rate of tax was 50%, and the lowest 10%, if tax revenues were to be maintained when switching to a flat tax system, then it would be impossible to simply extend the 10% rate of tax to all, as this would mean a large effective drop in revenue (as 40% less is collected from the top bracket with no gains anywhere), and so the rate paid by all would have to be somewhere between 10% and 50%, meaning an effective tax rise on the poorest and middle classes, while the richest receive an effective tax cut. This hardly seems 'fair' or in keeping with the aims of a welfare state, as the argument purports to serve.  [1] Ulbrich, Holley. “Flat Tax Is Class Warfare”. U.S. News &amp; World Report. April 12, 2010.