Almost all businesses need an Employer Identification Number (EIN) from the IRS before opening for business. From time to time, businesses may need to verify an EIN to maintain federally required records, research another company or to prove their right to various forms of information. The number is sometimes referred to as the Taxpayer Identification Number.
All corporations and partnerships must apply to the IRS for an EIN. Applications can be submitted online. A sole proprietorship has to apply for an EIN if her business has any employees, operates a Keogh plan, works with estates or trusts or files Alcohol, Tobacco and Firearms returns, among other conditions. A sole proprietor who doesn't need to use an EIN will use her Social Security number as the business identifier on her tax return.
If you're required to file any sort of form or statement that includes the EIN of a vendor or other company with which you do business, you need that company's EIN, and you need to verify the EIN. You can also use an EIN to identify a company and obtain information about it and track it regardless of any name changes. When dealing with sensitive medical information about your employees or trying to verify their immigration status, you may need to confirm your own EIN to obtain information.
If you're trying to make sure your own EIN is correct before you submit any paperwork, or if you've forgotten or misplaced your EIN, you can check with the IRS. If you're concerned about another company, you can ask the business for its number or use a company such as Westlaw, KnowX or FEIN Search, which, for a fee, will verify an EIN and may be able to provide added information about the company identified by the number.
Keep in mind that a company may not keep the same EIN indefinitely. A sole proprietorship has to change or acquire an EIN if it becomes a partnership or corporation or if it enters bankruptcy. A corporation that undergoes a merger or receives a new charter will likewise have to reapply for an EIN. An EIN is still a helpful guide, however: It survives name changes, location changes and corporate and partnership bankruptcies.