Wis. Stat. § 61.27
In all villages not assessed by a county assessor the assessor shall take and file the official oath. The assessor shall begin under s. 70.10 to make an assessment of all of the property in the village liable to taxation, as prescribed by law. The assessor shall return the assessment roll to the village clerk at the same time and in the same manner in which town assessors are required to do. The assessor's compensation shall be fixed by the village board. No person may assume the office of village assessor unless certified by the department of revenue under s. 73.09 as qualified to perform the functions of the office of assessor. If a person who has not been so certified is elected to the office, the office shall be vacant and the appointing authority shall fill the vacancy from a list of persons so certified by the department of revenue.
Wis. Stat. § 61.27