A W-9 is a tax document that confirms your status as a U.S. person for tax purposes. This form asks you to verify personal details such as your name, address, and Social Security number. Additionally, you'll need to indicate whether or not the IRS has informed you that you're subject to backup withholding.
If you’re a U.S. person for tax purposes and have a SoFi account that requires a W-9, you can complete the tax certification when you log in to your SoFi account in the app or on the web.