A federal tax ID number refers to the employer identification number (EIN) or Taxpayer Identification Number (TIN) assigned to business entities by the Internal Revenue Service. These are private identification numbers in most cases and difficult to find if you are not an authorized representative of the company. There are some databases that do provide EIN information for specific types of companies that are required to maintain public records.

Tax-Exempt Organization Database

Tax-exempt organizations are companies formed as corporations through a state's office of the secretary of state. The company then gets a TIN by completing IRS Form SS-4. In order to obtain the tax-exempt status, the corporation then applies for this status with the IRS. Once approved, the company's status is maintained in the Exempt Organization Select Check database. Search current and lapsed exempt status and obtain TIN information via this database. Searching by company name and state might yield a list of possible results. Use other data such as address or the director's name to confirm you obtain the correct TIN.

Search the Securities Exchange Commission Registration

It is federally mandated that any company raising one million dollars or more must register with the Securities Exchange Commission (SEC). This means any company that files tax forms 8-K, 10-K or 10-Q reports on corporate tax returns is maintained in a free public database called EDGAR. This database is maintained by the SEC. Because the database is so expansive, having as much company information as possible helps narrow the search results to find the correct company. Have the company legal name and address at a minimum. Executive board members' names are also helpful to cross-reference information.

Medical Provider Databases

While doctors function in privately held business entities, most belong to provider networks. Provider networks are the health networks for insurance benefit purposes. It is possible to search a provider's network database to locate a specific doctor or medical group's TIN. Once again, having as much information helps ensure you obtain the correct TIN matching the doctor's name, place of business and medical practice specialty.

Ask the Company

If you have a valid business reason, a company should provide you with TIN information. Employees need TIN information to complete tax returns. This information is usually on payroll paperwork or year-end W2 forms. Independent contractors making more than $600 from any one business contract need to report this. Most companies send a 1099-MISC for those contracts. If a contracted company hasn't sent TIN information to appropriately process tax forms, the company has a legitimate reason to request the TIN directly from the business. The contracted company also has a legitimate reason to request TIN information from the business that paid it.