Income tax return for taxation also vary, making comparisons all the more difficult. Countries that tax income generally use one of two systems: territorial or residential. In the territorial system, only local income – income from a source inside the country – is taxed. In the residential system, residents of the country are taxed on their worldwide (local and foreign) income, while nonresidents are taxed only on their local income. In addition, a very small number of countries, notably the United States, also tax their nonresident citizens on worldwide income. Countries with a residential system of taxation usually allow deductions or credits
Working Tax Credit from the earlier benefit for working families known as Family Credit (FC), which had been in operation since 1986. The WFTC shared its assessment of means and period of renewal (6 months) with FC but moved towards a tax credit approach styled on schemes in other countries, which used an annual declaration of income to assess entitlement for a whole year. Tax credits also replaced the child elements in means tested benefits, the Children's Tax Credit in the tax system, and disabled persons tax credit. In 2014 WTC and CTC combined cost £30 billion per year. The basic operation of