Find out the EIN number of a public company by searching its filing with the Securities and Exchange Commission, or SEC. Private companies are not required to disclose their ID numbers, although some add it to a public annual report.
When checking for a public company's EIN number, check the 10-K and 20-F forms found in its public files with the SEC. Find the EIN for a non profit company by checking its IRS Form 990 under the tax ID or EIN section for a nine-digit number. Nonprofits make those forms available to the public, but the forms are available by request at the non profit or a service that gathers that kind of documentation.
To find a private company's annual report, consult its website or contact the company directly. If there is not an annual report on file, search the company's public documents, including business filings with the secretary of state's office, bankruptcy filings or lawsuits. Some business and public records databases exist with this kind of information, as well.
If the company is your own and you have misplaced the number, search for the letter or email from the IRS confirming the receipt for your tax ID application. The number is usually at the top right hand corner of any correspondence between the IRS and the company. If you work for the company, contact the human resources or accounting departments and request the information. You may need to submit a reason why you need the information.