Kentucky: KRS § 139.470
KRS § 139.470. Exempt Transactions.
There are excluded from the computation of the amount of taxes imposed by this chapter [Sales and Use Taxes]:
(1) Gross receipts from the sale of, and the storage, use, or other consumption in this state of, tangible personal property or digital property which this state is prohibited from taxing under the Constitution or laws of the United States, or under the Constitution of this state.