If you want to get paid, you may need to submit a W9 form. Photo: David Goehring, Flickr

If you're a freelancer, consultant, or contractor, or are self-employed in some other capacity, there's a good chance you'll run across the IRS W9 form. It's not as well known as other tax forms, such as the 1040 or W-2, but it's still important.

In a nutshell
The official name of the IRS W9 form is "Request for Taxpayer Identification Number and Certification." It's a document you give to a business that will pay you, not one that you need to send to the IRS. It exists because businesses that pay you need your name, address, and tax identification number, so that they can later inform the IRS how much they paid you and can also send you a 1099 form come tax time. (The IRS wants to hear how much payers pay workers, so that they can match up those numbers with amounts the workers themselves report on their tax returns.) Sure, the businesses might just ask you to jot down your name, address, and tax identification number on a napkin or Post-it, but instead we have the W9 form.

For many, if not most, folks, their tax identification number is generally their Social Security number, or SSN. But if you run a sole proprietorship, it could be your Social Security number or your Employer Identification Number, or EIN, though the SSN is preferred. If your business is a single-member limited-liability company, or LLC, the SSN is generally the right number to use, and if your business is a partnership or multi-member LLC, you should use the EIN. (For many more details, check out the W9 form itself and its accompanying instructions.)

Details, details ...
Here are a few more things to know about the W9 form:

  • If you're a regular employee at a company, you probably won't have to deal with the W9 form. Employees instead typically have to submit a W-4  form, which provides their name, address, SSN, and information to help the employer determine how much tax to withhold from paychecks.

  • If you've been hired as an employee by a company and are asked to submit a W9 form, you might want to double check to make sure you're not being classified as an independent contractor. Many companies are shifting their workload from employees to contractors and freelancers these days in order to save money. After all, non-employees don't get benefits such as health insurance, retirement plans, and Pizza Day once a month.

  • Certain financial institutions that pay dividends or interest or some other kind of income might require a W9 form, but that typically isn't necessary, as they should have gotten your SSN and address when you opened your account. Be sure any request for a W9 form is legitimate, lest you share your SSN with any unscrupulous party interested in identity theft.

  • Along the same lines, don't leave the form lying around or send it to the company in an unsecured way, such as in an unencrypted email attachment or in a fax that might be left lying around before its recipient picks it up. Remember that it has exactly what an identity thief craves: your name, address, and SSN.

  • If you change your name, your business's name, your tax identification number, or your address, you should submit new W9 forms to the businesses that pay you, so their records are up to date and any information they send to the IRS will still match information you provide.

  • Finally, remember this: Avoid errors and don't think about any funny business, either. When you fill out the IRS W9 form, you sign it and essentially vouch for the truthfulness of the information it contains. So provide accurate information on the form.

For a tax form -- and, really, for any form -- the W9 is simple and easy.