​​Effective for taxable years beginning on or after January 1, 2009, the top individual income tax rate is increased from 6.75% to 7.75% (2009 Wisconsin Act 28). The increased rate applies as follows:

• Fiduciaries, single individuals, and heads of households – On all taxable income exceeding $225,000.
• Married persons filing joint returns – On all taxable income exceeding $300,000.
• Married persons filing separately – On all taxable income exceeding $150,000.

Interest on underpayment of estimated tax will not be charged when the estimated tax was underpaid due to the change in brackets. This applies only to the taxable year to which the bracket changes apply.

(Note: Publication W-166, Wisconsin Employer's Withholding Tax Guide is currently being revised to reflect this change.)

July 6, 2009