What is a W-8BEN? A W-8BEN is a certificate that is held on file by the payor of US income. It is used to prove to the IRS that they checked correctly, whether or not they (as payor) need to withhold US tax on any payment made to you, It also allows you to prove to them, that no tax (or a reduced rate of tax) is due to be withhold as a result of a tax treaty being in place between your home country of residence and the US. How long is a W-8BEN valid for? A W-8BEN is valid fo