​​​Taxpayers can self-report underpayment interest (UPI) on their Wisconsin income tax return. When the return is processed, department systems also calculate any UPI that may be owed. To avoid sending adjustment notices for small amounts because our system calculated more or less UPI than was self-reported, the department has a UPI tolerance. If self-reported UPI is less than $20, we will adjust the UPI to zero. (In other words, taxpayers do not have to self-report UPI under $20.)

If the amount of UPI owed is $20 or more and our system calculates a different amount than what was self-reported, a notice may or may not be sent to the taxpayer depending on tolerances on other lines of the income tax return. Also, see the article above about those who electronically file before April 15 and show an amount owed.

April 3, 2009