Wis. Stat. § 71.06

(1) Fiduciaries, single individuals and heads of households; 1986 to 1997. The tax to be assessed, levied and collected upon the taxable incomes of all fiduciaries, except fiduciaries of nuclear decommissioning trust or reserve funds, and single individuals for taxable years beginning on or after August 1, 1986, and before January 1, 1994, and upon the taxable incomes of all fiduciaries, except fiduciaries of nuclear decommissioning trust or reserve funds, and single individuals and heads of households for taxable years beginning after December 31, 1993, and before January 1, 1998, shall be computed at the following rates: (a) On all taxable income from $0 to $7,500, 4.9%. (b) On all taxable income exceeding $7,500 but not exceeding $15,000, 6.55%. (c) On all taxable income exceeding $15,000, 6.93%. (1m) Fiduciaries, single individuals and heads of households; 1997 to 1999. The tax to be assessed, levied and collected upon the taxable incomes of all fiduciaries, except fiduciaries of nuclear decommissioning trust or reserve funds, and single individuals and heads of households shall be computed at the following rates for taxable years beginning after December 31, 1997, and before January 1, 2000: (a) On all taxable income from $0 to $7,500, 4.77%. (b) On all taxable income exceeding $7,500 but not exceeding $15,000, 6.37%. (c) On all taxable income exceeding $15,000, 6.77%. (1n) Fiduciaries, single individuals and heads of households; 2000. The tax to be assessed, levied and collected upon the taxable incomes of all fiduciaries, except fiduciaries of nuclear decommissioning trust or reserve funds, and single individuals and heads of households shall be computed at the following rates for taxable years beginning after December 31, 1999, and before January 1, 2001: (a) On all taxable income from $0 to $7,500, 4.73%. (b) On all taxable income exceeding $7,500 but not exceeding $15,000, 6.33%. (c) On all taxable income exceeding $15,000 but not exceeding $112,500, 6.55%. (d) On all taxable income exceeding $112,500, 6.75%. (1p) Fiduciaries, single individuals and heads of households; after 2000. The tax to be assessed, levied and collected upon the taxable incomes of all fiduciaries, except fiduciaries of nuclear decommissioning trust or reserve funds, and single individuals and heads of households shall be computed at the following rates for taxable years beginning after December 31, 2000: (a) On all taxable income from $0 to $7,500, 4.6%. (b) On all taxable income exceeding $7,500 but not exceeding $15,000, 6.15%. (c) On all taxable income exceeding $15,000 but not exceeding $112,500, 6.5%. (d) On all taxable income exceeding $112,500, 6.75%.

(2) Married persons. The tax to be assessed, levied and collected upon the taxable incomes of all married persons shall be computed at the following rates: (a) For joint returns, for taxable years beginning after July 31, 1986, and before January 1, 1998: 1. On all taxable income from $0 to $10,000, 4.9%. 2. On all taxable income exceeding $10,000 but not exceeding $20,000, 6.55%. 3. On all taxable income exceeding $20,000, 6.93%. (b) For married persons filing separately, for taxable years beginning after July 31, 1986, and before January 1, 1998: 1. On all taxable income from $0 to $5,000, 4.9%. 2. On all taxable income exceeding $5,000 but not exceeding $10,000, 6.55%. 3. On all taxable income exceeding $10,000, 6.93%. (c) For joint returns, for taxable years beginning after December 31, 1997, and before January 1, 2000: 1. On all taxable income from $0 to $10,000, 4.77%. 2. On all taxable income exceeding $10,000 but not exceeding $20,000, 6.37%. 3. On all taxable income exceeding $20,000, 6.77%. (d) For married persons filing separately, for taxable years beginning after December 31, 1997, and before January 1, 2000: 1. On all taxable income from $0 to $5,000, 4.77%. 2. On all taxable income exceeding $5,000 but not exceeding $10,000, 6.37%. 3. On all taxable income exceeding $10,000, 6.77%. (e) For joint returns, for taxable years beginning after December 31, 1999, and before January 1, 2001: 1. On all taxable income from $0 to $10,000, 4.73%. 2. On all taxable income exceeding $10,000 but not exceeding $20,000, 6.33%. 3. On all taxable income exceeding $20,000 but not exceeding $150,000, 6.55%. 4. On all taxable income exceeding $150,000, 6.75%. (f) For married persons filing separately, for taxable years beginning after December 31, 1999, and before January 1, 2001: 1. On all taxable income from $0 to $5,000, 4.73%. 2. On all taxable income exceeding $5,000 but not exceeding $10,000, 6.33%. 3. On all taxable income exceeding $10,000 but not exceeding $75,000, 6.55%. 4. On all taxable income exceeding $75,000, 6.75%. (g) For joint returns, for taxable years beginning after December 31, 2000: 1. On all taxable income from $0 to $10,000, 4.6%. 2. On all taxable income exceeding $10,000 but not exceeding $20,000, 6.15%. 3. On all taxable income exceeding $20,000 but not exceeding $150,000, 6.5%. 4. On all taxable income exceeding $150,000, 6.75%. (h) For married persons filing separately, for taxable years beginning after December 31, 2000: 1. On all taxable income from $0 to $5,000, 4.6%. 2. On all taxable income exceeding $5,000 but not exceeding $10,000, 6.15%. 3. On all taxable income exceeding $10,000 but not exceeding $75,000, 6.5%. 4. On all taxable income exceeding $75,000, 6.75%. (2e) Bracket indexing. For taxable years beginning after December 31, 1998, and before January 1, 2000, the maximum dollar amount in each tax bracket, and the corresponding minimum dollar amount in the next bracket, under subs. (1m) and (2) (c) and (d) , and for taxable years beginning after December 31, 1999, the maximum dollar amount in each tax bracket, and the corresponding minimum dollar amount in the next bracket, under subs. (1n) , (1p) , and (2) (e) , (f) , (g) , and (h) , shall be increased each year by a percentage equal to the percentage change between the U.S. consumer price index for all urban consumers, U.S. city average, for the month of August of the previous year and the U.S. consumer price index for all urban consumers, U.S. city average, for the month of August 1997, as determined by the federal department of labor, except that for taxable years beginning after December 31, 2000, and before January 1, 2002, the dollar amount in the top bracket under subs. (1p) (c) and (d) , (2) (g) 3. and 4. and (h) 3. and 4. shall be increased by a percentage equal to the percentage change between the U.S. consumer price index for all urban consumers, U.S. city average, for the month of August of the previous year and the U.S. consumer price index for all urban consumers, U.S. city average, for the month of August 1999, as determined by the federal department of labor. Each amount that is revised under this subsection shall be rounded to the nearest multiple of $10 if the revised amount is not a multiple of $10 or, if the revised amount is a multiple of $5, such an amount shall be increased to the next higher multiple of $10. The department of revenue shall annually adjust the changes in dollar amounts required under this subsection and incorporate the changes into the income tax forms and instructions. (2m) Rate changes. If a rate under sub. (1) , (1m) , (1n) , (1p) or (2) changes during a taxable year, the taxpayer shall compute the tax for that taxable year by the methods applicable to the federal income tax under section 15 of the internal revenue code. (2s) Nonresidents and part-year residents. (a) For taxable years beginning after December 31, 1996, and before January 1, 1998, with respect to nonresident individuals, including individuals changing their domicile into or from this state, the tax brackets under subs. (1) and (2) shall be multiplied by a fraction, the numerator of which is Wisconsin adjusted gross income and the denominator of which is federal adjusted gross income. In this paragraph, for married persons filing separately "adjusted gross income" means the separate adjusted gross income of each spouse, and for married persons filing jointly "adjusted gross income" means the total adjusted gross income of both spouses. If an individual and that individual's spouse are not both domiciled in this state during the entire taxable year, the tax brackets under subs. (1) and (2) on a joint return shall be multiplied by a fraction, the numerator of which is their joint Wisconsin adjusted gross income and the denominator of which is their joint federal adjusted gross income.