The purpose of this form is to obtain or verify the accuracy of information regarding Alameda County's payees. Foreign vendors do not complete the Substitute Form W-9; foreign persons or entities must submit one of five available forms.New line 3b has been added to this form. To sum up: one of the biggest differences between the W9 and the W8 is that W8 is for nonUS citizens or US citizens based outside of the US. Only USbased companies need to collect Forms W8 or W9. If a company is based outside of the US, there's no need to collect them.