Income tax in the Netherlands (personal, rather than corporate) is regulated by the Wet inkomstenbelasting 2001 (Income Tax Law, 2001). The fiscal year is the same as the calendar year. Before May 1 citizens have to report their income from the previous year. The system integrates the income tax with fees paid for the general old age pension system (AOW), the pension system for partners of deceased people (ANW), and the national insurance system for special medical care (WLZ). There are three categories of income, each with their own tax rates. They are referred to as "boxes". Progressive tax on wages etc. (box 1) There is a progressive tax on wages, 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 the part of income up to €18,218: 2.3%; tax on €18,218 is €419 For the part of income between €18,219 and €32,738: 10.8%; tax on €14,520 is €1,568 For the part of income between €32,739 and €54,367: 42%; tax on €21,629 is €9,084 On all income over €54,367: 52% 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 is as follows: For the part of income up to €18,218: 33.45%; tax on €18,218 is €6,094 For the part of income between €18,219 and €32,738: 41.95%; tax on €14,520 is €6,091 For the part of income between €32,739 and €54,367: 42%; tax on €21,629 is €9,084 On all income over €54,367: 52% For 2011, income tax for people under the age 65 is as follows: For the part of income up to €18,628: 1.85%; tax on €18,628 is €345 For the part of income between €18,629 and €33,436: 10.8%; tax on €14,808 is €1,599 For the part of income between €33,437 and €55,694: 42%; tax on €22,257 is €9,348 On all income over €55,694: 52% For 2011, 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