The IRS does not mention that income in the amount of $600 or more is to be reported on a W9 form. The IRS states (as seen below) that the W9 is to use to report income paid to you, real estate transactions, mortgage interest you paid, acquisition or abandonment of secured property, cancellation of debt, or contributions you made to an IRA.
Purpose of the W9 Form (from the IRS website)
A person who is required to file an information return with the IRS must obtain your correct taxpayer identification number (TIN) to report, for example, income paid to you, real estate transactions, mortgage interest you paid, acquisition or abandonment of secured property, cancellation of debt, or contributions you made to an IRA.
Use Form W-9 only if you are a U.S. person (including aresident alien), to provide your correct TIN to the person requesting it (the requester) and, when applicable, to:
1. Certify that the TIN you are giving is correct (or you are
waiting for a number to be issued),
2. Certify that you are not subject to backup withholding, or
3. Claim exemption from backup withholding if you are a U.S.
exempt payee. If applicable, you are also certifying that as a
U.S. person, your allocable share of any partnership income from
a U.S. trade or business is not subject to the withholding tax on
foreign partners’ share of effectively connected income.
3. I am a U.S. citizen or other U.S. person (defined below).
A person who is required to file an information return with the
IRS must obtain your correct taxpayer identification number (TIN)
to report, for example, income paid to you, real estate
transactions, mortgage interest you paid, acquisition or
abandonment of secured property, cancellation of debt, or
contributions you made to an IRA.
Individual/Sole proprietor
Corporation
Partnership
Other (see instructions) ©
Note. If a requester gives you a form other than Form W-9 to request your TIN, you must use the requester’s form if it is substantially similar to this Form W-9.
For a table of contents and the full instructions for the requester of Form W9 click the following link: http://www.irs.gov/instructions/iw9/index.html