An Employer Identification Number (EIN) is a nine-digit unique number that the Internal Revenue Service assigns to businesses that are required to file tax returns including corporations, partnerships, nonprofit organizations, sole proprietors, government bodies, churches, trusts and estates. If a company you are researching has an EIN, you know that the company is required to file tax returns which would include information about the company's assets as well as some if not all of the executives for the company.

If you do not have a company's Employer Identification Number and need to find it, there are several ways to try to locate the EIN. Public companies print the EIN on the first page of their 10-Ks, 20-Fs and other SEC filings. You can locate these documents for free through the U.S. Securities and Exchange Commission's EDGAR database.

Nonprofit organizations often include the EIN on the Form 990 which provides a nonprofit organization's financial information and executive names. GuideStar, which is a nonprofit organization Website, maintains a database with several organizations' Form 990. The basic GuideStar search is a free service that requires an ID (e-mail) and password to access the Form 990.

For private companies you can try looking at the company Website, a company invoice or try fee-based resources such as Westlaw (BUS-TRACK) or Lexis (D&B/FEIN). EINs are also called FEINs ("Federal Employer Identification Numbers") and TINs ("Taxpayer Identification Numbers").