Taken directly from– U.S. Tax Treaties:
“Application of Treaties
The United States has income tax treaties with a number of foreign countries. Under these treaties, residents (not necessarily citizens) of foreign countries are taxed at a reduced rate, or are exempt from U.S. income taxes on certain items of income they receive from sources within the United States. These reduced rates and exemptions vary among countries and specific items of income.
Many of the individual states of the United States tax the income of their residents. Therefore, you should consult the tax authorities of the state in which you live to find out if that state taxes the income of individuals and, if so, whether the tax applies to any of your income.
Residents of Pakistan who perform personal services (including professional services) for or on behalf of a resident of Pakistan while in the United States for no more than 183 days during the tax year are exempt from U.S. income tax on the income from the services if they are subject to Pakistani tax.”
This stuff is complex. That’s why you should contact a professional. If you’re interested in seeking the advice of an attorney who has experience helping foreign business owners then check out.