Wis. Stat. § 70.365

When the assessor assesses any taxable real property, or any improvements taxed as personal property under s. 77.84 (1) , and arrives at a different total than the assessment of it for the previous year, the assessor shall notify the person assessed if the address of the person is known to the assessor, otherwise the occupant of the property. The notice shall be in writing and shall be sent by ordinary mail at least 15 days before the meeting of the board of review or before the meeting of the board of assessors in 1st class cities and in 2nd class cities that have a board of assessors under s. 70.075 and shall contain the amount of the changed assessment and the time, date and place of the meeting of the local board of review or of the board of assessors. However, if the assessment roll is not complete, the notice shall be sent by ordinary mail at least 15 days prior to the date to which the board of review has adjourned. The assessor shall attach to the assessment roll a statement that the notices required by this section have been mailed and failure to receive the notice shall not affect the validity of the changed assessment, the resulting changed tax, the procedures of the board of review or of the board of assessors or the enforcement of delinquent taxes by statutory means. The secretary of revenue shall by rule prescribe the form of the notice required under this section. The form shall include information notifying the taxpayer of the procedures to be used to object to the assessment.