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 income tax benefit 453 of the income tax return if their income exceeds $3,000 for the calendar year. However, the additional paperwork required to claim the credit is complex, involving a the 42-step process on Schedule 6 of Canada's main income-tax form. As of 2016, the WITB is worth up to $1,028 for a single individual and $1,868 for couples and single-parent families. Benefits increase and then decrease with income. At an income of $18,529 for single individuals or $28,576 for families the benefits decrease to $0. WITB is estimated to benefit 1.4 million working Canadians annually, at a cost to the federal