Who is require to withhold? • Withholding Agent.If you employ workers from outside the US, you need to provide them with a W8BEN form. Under most tax treaties, foreign companies are subject to federal tax if their US business activities rise to the level of a permanent establishment. This page provides links to tax treaties between the United States and particular countries. If the foreign entity comes from a country with a U.S. tax treaty, they can fill out and submit a W-8BEN-E form. The company is usually the party responsible for withholding any required tax when it pays a foreign contractor for services performed in the United States.