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
Income tax in the Netherlands as "boxes". There is a progressive tax on wages, profits, social security benefits and pensions. Thus there are tax brackets, each with its own tax rate. Mathematically, apart from discretization (whole euros both for income and for tax), the tax is a continuous, convex, piecewise linear function of income. For 2010, income tax for people under the age 65 is as follows For 2010, the total tax on income (income tax plus mandatory pension, social security and state funded medical care payments, all of which are a percentage of income up to a maximum) for people under the age 65