EIN numbers can be verified through several tax documents, such as a W-9 for the company or an employee W-2 form that contains the employer's EIN. An EIN number is the Employer Identification Number the IRS assigns to a business.
An EIN is also known as a Taxpayer Identification Number (TIN). A business uses a W-9 form to convey its tax status to other parties it does business with, apart from an employer standpoint. The W-9 shows the EIN as well as the structure of the entity (such as a corporation or partnership). Employees can find the EIN for their employer stated on the W-2 and use it when filing their individual taxes.