Why a flat tax is regressive  'Regressive' means that a tax impacts upon the poor more greatly than upon the rich, and this is exactly what occurs with a flat tax. Because everyone pays the same percentage, both a rich and poor man would for example pay 10% of their income in tax. As the poor spend a greater percentage of their income on their basic necessities (such as rent and food) than the rich do, as the rich have far more discretionary income to spend on luxuries. [1] Therefore, the impact of a 10% tax upon a poorer person is far greater in terms of limiting their ability to buy things they may want or need than it is upon a richer person, and consequently the harm of taxing a poorer person at the same rate as a richer person is greater than the harm of taxing a richer person at a higher percentage. Even if the 'personal allowance' allows the poorest in our society to exempt their income from the flat tax (which, of course, offers no relief to the middle class, who now pay a greater percentage tax on their income), they will still be significantly worse off as a consequence of the sales component of the flat tax. This again stems from the poorest spending a greater percentage of their income on necessities, which are not currently subject to sales tax (VAT). Once these VAT 'loopholes' (such as on books, children's clothing and food) are closed, the poorest will be harmed as they have to pay out even more to obtain the necessities of life. Both These increased harms breed resentment and can lead to social disorder, as was seen in the UK in 1990 when an attempt to introduce a 'poll tax' (a form of flat tax, with everyone paying the same charge) led to severe rioting in London and caused the plan to be abandoned. [2] Therefore the regressive nature of a flat tax makes it undesirable and more harmful than current forms of taxation.  [1] Encyclopedia of Business. “Discretionary Income”. Enotes.   [2] BBC On This Day “1990: Violence flares in poll tax demonstration” BBC Home