Businesses that operate in the U.S. either apply for and are issued a federal employers tax identification number or use the Social Security number of the sole proprietor as their tax ID number. There are a several easy and free ways to search for the tax ID that a business is operating with.
Use the U.S. Securities and Exchange Commission's EDGAR database to locate publicly traded companies' tax ID numbers by accessing their website (see Resources).
Complete as much information regarding the company as you know before hitting the Find Companies button.
Locate the tax ID number that will be listed as the IRS number on the individual filings.
Use the Guidestar program to locate a nonprofit organization's tax ID number by accessing their website (see Resources).
Register as a user on the website by clicking the register button on that page, completing the next page and agreeing to the user agreement.
Obtain the confirmation email in your inbox; click the link in that email to activate your account, which will return you to the Guidestar homepage.
Locate the organization by typing as much information as you know about the organization into the search box before hitting the Start Your Search Button.
Click on their name, after the company is located, then click on the form number 990 tab, on which you will find the tax ID number.
If you have misplaced your own business's tax ID you can call the IRS Business & Specialty Tax line at (800) 829-4933 to obtain it. There are also fee-based options for obtaining a business's tax ID like Westlaw's BUS-TRACK and/or FEIN-ALL programs and Lexis' D&B/FEIN Search program. If you are looking for the tax ID so that you can file a 1099 (or other information return) for the company, have the company complete a form W-9 and submit it to you.