An EIN is a unique number the IRS gives to businesses (including sole proprietors), government bodies, churches, trusts and estates for tax identification purposes. EINs have two digits, a dash and then seven more digits (e.g., 75-6948657).
Applying for an EIN: You can apply for an EIN by getting Form SS-4 from the IRS Web site (http://www.irs.gov/formspubs) and then contacting the IRS by fax, phone or mail (as explained in the instructions for the SS-4).
To find a company's EIN: EINs are easy to find for public companies, a little harder for private companies.
For public companies, the EIN (or "IRS No.") is printed on the first page of 10-Ks, 20-Fs and other SEC filings, which you can get on the Internet for free (see the Filings section of "Securities and Exchange Commission").
For private companies, you can search FreeErisa's EIN Finder or FEINsearch.com, or use the EIN field in the business search on a public records database such as KnowX.com, TLO, Accurint, Lexis (D&B;FEIN) or Westlaw (FEIN-ALL). If the company files with a Secretary of State the EIN may be on its annual report. If the company filed for bankruptcy, the EIN may be on the docket sheet as part the company's address. Also, EINs are often included in the company's D&B report (see "Dun & Bradstreet Reports").
For non-profits, EINs are often included in the the profile on Form 990, available through Guidestar, the Foundation Center's 990 Finder and Noza. In addition, nonprofit EINs are often included in the records in the Lexis EOTEXT file.
For political parties and other political organizations, EINs are reported on Form 8871, available through the IRS Web site.
For insurance companies, the number should be at the top of their annual financial statement, which you can get if you dig deep enough on the NAIC Web site.
If that doesn't work, UCC filings sometimes have EINs, though they usually don't (see also "Uniform Commercial Code").
FEINs: FEINs ("Federal Employer Identification Numbers") are apparently the same thing as EINs. An IRS representative told me that the IRS doesn't use the "F," and it's probably just a way some databases distinguish the EIN from any other identification number issued by a state taxing authority.
TINs: TINs ("Taxpayer Identification Numbers") are the equivalent of Employer Identification Numbers for people. Usually your TIN is the same as your Social Security Number.