An Employer Identification Number is a unique number assigned to a business for tax purposes. If you're an employer, you'll need to specify your business's EIN for tax purposes; if you're an employee, you'll need to specify the EIN of the business that employs you. While there is no available directory of EINs, there are several places you can find the number, as either an employee or employer.
Find the confirmation the IRS sent you when you first registered for the EIN. This should be in your company records.
Contact any bank or license agency with which you dealt using your business's EIN. They will have the number on file, assigned to your account or license.
Contact the IRS Business & Specialty Tax Line. The number is (800) 829-4933, and the line is available 7 am to 10 pm local time, Monday through Friday. If you are authorized to receive the EIN, the IRS operator will provide you with it after you answer a few questions.
Check one of your pay stubs. The EIN number should appear somewhere on it -- where exactly depends on the format of the stub.
Check a W-2 form issued by your employer. This will always contain the EIN. On the 2010 form, it's in box "b".
Contact your employer and ask for their EIN. They should have it on file and won't be reluctant to supply it.
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