Definition for W-9
From Biology Forums Dictionary
A form used to certify a shareholder's social security or tax identification number as true and correct, in order to avoid federal tax withholding.
Request for Taxpayer Identification Number and Certification form required by the IRS to furnish the payer, transfer agent, broker or other middleman with an employee's social security or taxpayer identification number, in order that the employee not be subject to backup withholding because of under-reporting of interest and dividends on his or her tax return.