Wis. Stat. § 71.265

The Wisconsin adjusted basis of the property of any corporation that has, in any taxable year before it ceases to be exempt from tax under this chapter, taken depreciation or amortization of depreciable property for federal income tax purposes shall be the adjusted basis of that property as computed for federal income tax purposes as of the beginning of the taxable year INCOME AND FRANCHISE TAXES 71.2889 in which the corporation ceases to be exempt. The corporation may continue, after it ceases to be exempt, to depreciate that property under the method used previously for federal income tax purposes.