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 Prime Minister Tony Blair also apologised to Parliament over the incident. The Working Tax Credit scheme was subject to much criticism, particularly in the wake of the difficulties surrounding its implementation. Criticism focused on the way that credits are calculated on an annual basis, leading to overpayment, followed by large demands for repayment, which those on low income may find difficult to meet. David Harker, chief executive of Citizens Advice, commented "This is an untenable system. An annualised system doesn't provide the stability of income required by low income families." In addition, the scheme was accused of being over-complicated and