What is Form W-9?
Definition Form W-9 is a request for a taxpayer identification number that a business gives to a vendor, contractor, or other payee to collect the information needed to issue year-end 1099s. It is provided to the requesting business, not filed with the IRS. Collecting a completed W-9 before making payments avoids backup withholding and year-end scrambles.
Gathering W-9s up front makes 1099 season far smoother for a firm's business clients and reduces the risk of penalties for missing information.