When filling out a W-9 tax form as a self-employed person, enter your name and Social Security number, and sign the certification that you are exempt from backup withholding, reports About.com. If the Internal Revenue Service notifies you that you are subject to mandatory backup withholding, cross out the declaration in the second certification bullet point before signing the form. When filling out a Form W-9 as a business, enter the business name, employer identification number and correct tax classification.
If the tax classification of your business is C-corporation, S-corporation or partnership, tick the correct box, explains About.com. If your business is a limited liability company that belongs to another LLC, then tick LLC, but if it is an LLC with you as the sole owner, fill in your name, the business name and your Social Security number. The IRS may require financial institutions or businesses to withhold 28 percent of your income in backup withholding if you do not report your taxpayer identification number correctly, if the number you give doesn't match IRS records, if you underreport income or if you owe federal taxes.
Because the Form W-9 gives secure personal information, be sure you know who sends you the form. Do not send it as an attachment to an email message unless you encrypt it first. Alternatively, deliver it by hand, or send it by post. If a new employer asks you to fill out a Form W-9 but you should be an employee of the company, ask for a clarification of your status, as the Form W-9 is only for self-employed personnel. If you are an employee, fill out a Form W-4 instead, advises About.com.