Businesses in Missouri are required to file for both federal and state tax identification numbers. A company's employer ID number, or EIN, appears on every invoice and most financial documents from the company. If you need to find the employer ID number of a company based in Missouri, you can search for records both within the state and with the Securities and Exchange Commission (SEC,) a federal agency.
Contact the office of the Missouri Secretary of State. The Secretary of State's office is responsible for registering businesses in the State of Missouri, and can provide you with publicly available information about a Missouri business. See the Resources section for a link.
Contact the Missouri Department of Revenue. Businesses in Missouri are required to register with the State Department of Revenue for a State EIN.
Search for the company in the SEC's database, called "EDGAR." Publicly traded companies are required to list their EINs on the first page of their 10-K forms, 20-F forms, and other SEC filings. This paperwork is public and is available free through the SEC's database. Use the link in the Resources section to search the SEC's database.
Use the search service of Guide Star, a website for nonprofit organizations. According to the Department of Labor, nonprofit organizations often list their EIN on Form 990, which records a non-profit's financial information and the names of its executives. Guide Star has a searchable database which includes many organizations' Form 990. Guide Star is a free service, but requires registration with an email and password to access the forms. See Resources for a link.
Search for the company's records using a fee-based search service like Westlaw or Lexis. Many records are publicly available for free, so use these services as a last resort.