Hi and welcome to Just Answer!You may find IRS instruction on page 3 - http://www.irs.gov/pub/irs-pdf/fw9.pdf Part II. CertificationTo establish to the withholding agent that you are a U.S. person, or resident alien, sign Form W-9. You may be requested to sign by the withholding agent even if item 1, below, and items 4 and 5 on page 4 indicate otherwise.For a joint account, only the person whose TIN is shown in Part I should sign (when required). In the case of a disregarded entity, the person identified on the “Name” line must sign. Exempt payees, see Exempt Payee on page 3.Signature requirements. Complete the certification as indicated in items 1 through 3, below, and items 4 and 5 on page 4.1. Interest, dividend, and barter exchange accounts opened before 1984 and broker accounts considered active during 1983.You must give your correct TIN, but you do not have to sign the certification.2. Interest, dividend, broker, and barter exchange accounts opened after 1983 and broker accounts considered inactive during1983. You must sign the certification or backup withholding will apply. If you are subject to backup withholding and you are merely providing your correct TIN to the requester, you must cross out item 2 in the certification before signing the form.3. Real estate transactions. You must sign the certification. You may cross out item 2 of the certification.4. Other payments. You must give your correct TIN, but you do not have to sign the certification unless you have been notified that you have previously given an incorrect TIN. “Other payments” include payments made in the course of the requester’s trade or business for rents, royalties, goods (other than bills for merchandise), medical and health care services (including payments to corporations), payments to a nonemployee for services, payments to certain fishing boat crew members and fishermen, and gross proceeds paid to attorneys (including payments to corporations).5. Mortgage interest paid by you, acquisition or abandonment of secured property, cancellation of debt, qualified tuition program payments (under section 529), IRA, Coverdell ESA, Archer MSA or HSA contributions or distributions, and pension distributions. You must give your correct TIN, but you do not have to sign the certification.
Here are instructions for the requester - http://www.irs.gov/pub/irs-pdf/iw9.pdf