If you misplace your EIN, look for it on the notice sent to you by the IRS when your EIN was issued You can also try to recover it by contacting the financial institution where you do your day-to-day banking. You can also find it on your previous tax returns. If all else fails, contact the IRS' Business & Specialty Tax Line at 1-800-829-4933. Make sure you have any identifying information on hand before you speak to an operator.