What is the Purpose of an IRS W-9 Form?

Form W-9—Request for Taxpayer Identification Number and Certification—is one of the most commonly used IRS forms. If you’ve ever been an employee of a company, you’ve probably completed a Form W-9. True to its name, individuals and entities use the form to provide their taxpayer identification number to entities that will pay them income during the tax year. Your employer uses your W-9 for payroll purposes but doesn't send the form to the Internal Revenue Service. The information is used to prepare employee paychecks during the year and W-2 forms at the end of the year. If you have your own business or work as an independent contractor, a client may request that you provide a W-9 so they can accurately report the payments they make to you.
To complete Form W-9, you’ll need to enter your full name as shown on your federal income tax return on the first line. If you are operating a business under a separate name, you should enter that on the second line. In the next section, you select your tax classification. Most employed and self-employed taxpayers will select “Individual/Sole Proprietor”. Professionals who operate partnerships, corporations or estates should select the appropriate classification for their situation.
After you complete the mailing address section, you’ll need to enter your taxpayer identification number, or TIN. Generally, this is your Social Security number. Nonresident aliens who do not have Social Security numbers should enter their assigned TIN in this field.
If you’re running your own business and you have an employer identification number, you should enter that number next to the EIN field. Sign and date the form at the bottom.
The IRS sometimes requires the person or entity requesting the W-9 to withhold a percentage of your earnings to pay your federal income taxes. This is known as backup withholding. You will be notified by the IRS if you are subject to backup withholding. If so, you need to inform the company that you are providing the W-9 to that they need to withhold taxes from the money that they pay you.
If you are an employee, you’ll usually submit your completed Form W-9 to your supervisor or your company’s human resources department. Your employers typically will keep the completed form in your personnel file for reference during the payroll process.
