Wis. Stat. § 76.09: Assessment of omitted property.

Any property subject to assessment under this subchapter which has been omitted from assessment or which has not been included in any assessment already made in any of the 5 next previous years by mistake or inadvertence unless previously reassessed for the same year or years, shall be entered by the department upon its assessment and tax roll once additionally for each year so omitted, designating each additional entry as omitted for the year of omission and fixing the valuation and tax to each entry for a former year as the same should then have been assessed according to the best judgment of the department. The proceedings related to an assessment under this section shall be had and hearings given as far as practicable in accordance with this subchapter.