An employer identification number (EIN) for a company can compare to the Social Security number for an individual; it helps identify the organization when it comes to taxes and financial matters. If you forget or lose your own company's EIN, you can contact the IRS, look at old tax and financial documents or consult your EIN confirmation letter.

Finding the EIN number for a company you don't own can take more research since you probably don't have its tax and financial documents on hand. However, online databases, company websites and third-party services can help.

EIN Number for a Company

Obtained from the IRS website for free, an EIN has nine unique digits. In addition to using the number for handling taxes, a company might use an EIN number when it comes to applying for financing, filling out important legal documents and getting licensed.

It's important to note that the IRS doesn't require all companies to have an EIN. So, keep this in mind if you plan to search for the EIN of a company but end up unable to locate the number. In that case, the business owner might use his Social Security number for tax and financial purposes.

For example, corporations, partnerships, tax-exempt organizations and other companies that hire employees are among those that need an EIN. However, single-person businesses and S corporations might not need one. These kinds of businesses may still opt for an EIN since it can help separate personal and business finances and also provides some identity theft protection versus using a Social Security number.

Finding Your Own Company's EIN

If you need to find the EIN number of your company, the best place to start is to look for important IRS documentation. When you request your EIN from the IRS, you either got a confirmation letter physically mailed to you or you downloaded an electronic version that contains your EIN. If you've filed your taxes with the EIN, you will find your EIN listed near the top of your business tax return.

You can also try looking at other business documents that require an EIN. For example, you should be able to locate it on your business license or permit, financial documents like bank statements and any payroll paperwork.

When searching documents doesn't help, you can call 1-800-829-4933 to speak with the IRS and have them look up the number. This special tax line stays open on weekdays between 7 a.m. and 7 p.m. in your time zone. You should prepare to verify your identity and show that you're the company's owner, partner, trustee, corporate officer or another authorized individual.

Finding Another Company's EIN

If the company is publicly traded, first check if the company's website has an investors section on its website. You'll often find links to Securities and Exchange Commissions filings that will have the EIN listed in the documents. If you don't find any, visit the SEC's website to access the electronic data gathering, analysis and retrieval system, where you can look up a business's recent filings using the company's name.

If you need the EIN for a nonprofit business, the IRS has a tax-exempt organization search tool that allows you to search by organization name, city, state and country. The results will show the organization's EIN along with a link to click to see tax documents like determination letters, IRS Publication 78 data and copies of returns. You can also use a third-party search tool like GuideStar to look up the EIN and tax info for nonprofits.

If these methods don't help you find the EIN for the company, you can try calling the company's finance or accounting department directly to ask. You can also try researching online for business registration documents. If you don't mind paying a fee, the TINCheck service as well as the business's credit report can provide the EIN.