Answer by Randy Carey: Read the instructions for the W-9. The IRS indicates in the instructions that they prefer the individual's SSN.
Answer by John Burnett: And that is because the IRS doesn't need to use the EIN for any other purpose than employment and withholding tax reporting and depositing for the business's employees. All the rest of the sole proprietor's dealings with the IRS are via his/her annual personal tax return (1040), which is done with an SSN.
As a bank, it's to your advantage to use the SSN, too, because all the accounts of the sole proprietor are "at risk" if you are served with a garnishment, levy or similar legal seizure document, and having them all connected to the SSN is just handy.
First published on BankersOnline.com 7/30/12