…income tax, just like a “permanent establishment” under traditional U.S. income tax treaties. To limit local income taxation of interstate sales of goods, a 1959 law (Interstate Income Act of 1959, P.L. 86-272) protects interstate and international businesses by prohibiting states from imposing a net income tax on a business whose activities in the state are limited to soliciting orders for sales of tangible personal property. The 1959 law was ado…