should you choose not to furnish a form w 9 or if the information provided is incorrect a 24 withholding tax will be taken from future payments you receive from your client in addition there are penalties and fees for intentionally failing to furnish correct information or misuse of tins 
the bottom lineform w 9 is an irs tax form that requests information for an individual defined as a u s citizen or a person defined as a resident alien the information is used to fill out form 1099 and is used for independent contractors freelancers or unrelated vendors but not employees failing to fill out the form can result in penalties 