A written agreement (e.g. Contract, purchase order, statement of work, etc.) exists with the College that spells out the task(s) or service(s) to be performed.This guide is intended to simplify the process. Examples of common payments the University makes to foreign nationals visiting or working in the US. The first step is to have the contractor complete Form W9, Request for Taxpayer Identification Number and Certification. Avoid pitfalls when making payments to foreign contractors. Follow these 4 tips to ensure compliance with tax laws and avoid payroll errors.