Wisconsin: Wis. Adm. Code Tax 11.05
Wis. Adm. Code Tax 11.05 (Governmental units)
(4) NONTAXABLE RECEIPTS. Receipts by governmental units from the following are not taxable:
(f) Purchases by consular and diplomatic personnel of other countries which have entered into multilateral treaties with the United States government providing for sales and use tax exemptions are exempt provided the personnel present their tax exemption card issued by the United States department of state showing their tax exemption number.