The main difference between a W8 vs. 9 form identifies whether the payee is a citizen, resident, or foreigner for income tax purposes.Understand their roles of W8 vs. W9 forms in U.S. taxation, key differences, and get insights on how to fill them out. The company I am dealing with requested for a W-9 form. However, upon research I found out that I am supposed to submit a W8 form instead of a W9. The Form W9 is a short onepage form that asks for your name, address, and IRS tax identification number (SSN or ITIN in the case of an individual). Find out everything you need to know about W8 and W9 forms in the United States in our essential guide. Businesses should request a W9 from all vendors. Foreign vendors do not complete the Substitute Form W-9; foreign persons or entities must submit one of five available forms.