Wis. Stat. § 72.02: Estate tax imposed.

An estate tax is imposed upon the transfer of all property that is subject to a federal estate tax and that has a taxable situs in this state. The tax imposed is equal to the federal credit against the federal estate tax as finally determined. If only a portion of a decedent’s property has a taxable situs in this state, the tax imposed is the amount obtained by multiplying the federal credit by a fraction the numerator of which is the value of the decedent’s estate that has a taxable situs in this state and the denominator of which is the total value of the property in the estate that qualifies for the federal credit.