Wis. Stat. § 70.34: Personalty.

For assessments made before January 1, 2024, all articles of personal property shall, as far as practicable, be valued by the assessor upon actual view at their true cash value; and after arriving at the total valuation of all articles of personal property which the assessor shall be able to discover as belonging to any person, if the assessor has reason to believe that such person has other personal property or any other thing of value liable to taxation, the assessor shall add to such aggregate valuation of personal property an amount which, in the assessor’s judgment, will render such aggregate valuation a just and equitable valuation of all the personal property liable to taxation belonging to such person. In carrying out the duties imposed on the assessor by this section, the assessor shall act in the manner specified in the Wisconsin property assessment manual provided under s. 73.03 (2a).