The EDGAR system, which stands for Electronic Data Gathering, Analysis and Retrieval system, is maintained by the United States Securities and Exchange Commission. The EDGAR system tracks all the information filed by for-profit companies. Melissa Data is an organization that tracks the information of non-profit companies. Both have free databases.
Search for the company on the database by using its name. When using EDGAR, search with just the first few letters of the company name, because not all businesses are listed under the name they are most well known by. The federal tax identification number can be found on forms, such as the 8-K, 10-K and 10-Q forms. When using Melissa Data, you may search by name, zip code or tax identification number. Use the zip code of the corporate office instead of a local branch.
If you are unable to find the company's tax identification number on either database, ask the company if possible. A person in the accounting department should be able to provide the tax identification number.