Employer Identification Number (EIN) Definition: A 9-digit number obtained by a business with paid employees from the IRS. If you're a sole proprietorship, your EIN is your social security number.

Start your search now. The offers and details on ... usually be obtained the same day you apply for one on the IRS website. An EIN is mandatory for most businesses, and optional for others.

However, if the new EIN is not obtained online before a certain date in December, the tax practitioners and their clients may not get the transaction completed before year-end. This is because the ...