Wisconsin state law requires that all taxable property be valued annually on January 1. There are several reasons why an assessment might rise from one year to the next. If improvements are made to the property, such as the addition of a new room or garage, the value of the property is higher and the assessment might be changed to reflect the increase. In many municipalities, a building permit will alert the assessor to the improvement. In other cases, the sale price of the property, or of similar properties, might result in a change in the assessment.
Local assessors receive a copy of real estate transfer tax returns.
Any change in assessment should adjust the assessed value of the property to the general level of assessment of all comparable property in the community. Decreases While most property owners are concerned about assessment increases, they also should be alert for legitimate decreases. Events that might adversely affect property values include a contaminated water supply, a failing septic system, or significant changes in a neighborhood. All property within a municipality is periodically revalued. Property that previously was under assessed will have higher values assigned.