List all payees withheld upon during the filing period. Gov and search for withholding requirements for updates, online tools, and more information, including: Forms and PublicationsAt a minimum, information must be in the highlighted fields, but other boxes must be completed if the nature of the payment requires it. Payments made to foreign vendors will be subject to U.S. federal income tax withholding of 30 percent unless: 1. Prizes and Awards, which when paid to non-U. Setting aside the work permit issue, a foreign contractor working in the US should pay tax on his US sourced income.