Negative income tax notion has long been popular in some circles, its implementation has never been politically feasible. This is partly because of the very complex and entrenched nature of most countries' current tax laws: they would have to be rewritten under any NIT system. However, some countries have seen the introduction of refundable (or non-wastable) tax credits which can be paid even when there is no tax liability to be offset, such as the Earned Income Tax Credit in the United States and working tax credit in the UK. In 1971, President Richard Nixon proposed a negative income tax as the centerpiece
Working Tax Credit significant levels of overpayments. In order to reduce the overpayment problem, the income disregard was raised tenfold from £2,500 to £25,000 with effect from 2006/07. Income for tax credit purposes is "in principle" assessed similarly to UK income tax. Thus 'income' (c/f 'taxable income') consists of what the individual receives from gross earned and unearned sources—less allowances for 'expenditures' that would reduce that income. But, unlike income tax, tax credits measure income based on family 'household', rather than the individuals within. Also the effect of "income disregard" —to mask large annual increases in resources from reassessment— weakens comparisons with a