Wis. Stat. § 70.34
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).
Wis. Stat. § 70.34
"True cash value" is not a figure that can be determined by bargaining with the taxpayer, and such an agreement would be void. The unsupported statement of the taxpayer has no probative value. State ex rel. Berg Equipment Corp. v. Town of Spencer Board of Review, 53 Wis. 2d 233, 191 N.W.2d 892 (1971). When there are no actual sales, cost, depreciation, replacement value, income, industrial conditions, location and occupancy, sales of like property, book value, insurance carried, value asserted in a prospectus, and appraisals are all relevant to determination of market value for assessment purposes. State ex rel. Mitchell Aero, Inc. v. Board of Review, 74 Wis. 2d 268, 246 N.W.2d 521 (1976). A market data or sales approach was proper when 94 percent of machines were leased and only 6 percent were sold. An income capitalization approach has been used only when no sales exist. Xerox Corp. v. DOR, 114 Wis. 2d 522, 339 N.W.2d 357 (Ct. App. 1983).