A federal tax ID number, also known as an Employer Identification Number (EIN) is a nine-digit, unique number assigned by the Internal Revenue Service (IRS). The EIN is used by the IRS for tax-related purposes. The EIN is also called the Employer Tax ID or Form SS-4. If you've misplaced your business's EIN, or want to look up the EIN for another business, there are several resources that can assist you.

Your Business's EIN

Look through your files and try to locate the IRS confirmation letter that listed your EIN.

Call the IRS's Business and Specialty Tax Line at (800) 829-4933 and ask them to locate your EIN. You'll need to provide identifying information to prove you should have access to the EIN.

Contact any banks with whom you have done business. You would have needed the EIN to open a business checking account or to obtain a loan. The bank will have your EIN on file.

Searching for Another Business's EIN

Search for a public company's EIN on page one of 10-Ks, 20-Fs and other Securities and Exchange Commission (SEC) filings. You can perform a free search through the SEC's Electronic Data Gathering and Retrieval (EDGAR) database (see Resources).

Navigate to Guidestar's online database (see Resources) and perform a search for a nonprofit's Form 990. Nonprofit organizations often list their EIN on that form.

Look on a company's website for their EIN number or check old invoices and tax records (like W2s). You may also be able to obtain the EIN by calling the company's accounting department and asking for the number.


You can obtain the EIN by writing to the IRS and requesting it. You should give your full name and address and state your reason for needing the EIN. Allow 4-6 weeks for a response.