Limited liability companies (LLCs) entail legal protection of the members' personal assets without the formal regulations of corporations. Owners of an LLC are called members, which can be a single individual, a corporation, another LLC or a foreign entity. Many single-member LLCs choose to use the Social Security number of the owner in lieu of a federal tax ID number (TIN). Other LLCs with many employees choose to apply for a TIN in order to protect the Social Security number of the owner. If you need to find a TIN for an LLC, a few resources can help you.

Check the United States Securities and Exchange Commission (SEC) EDGAR database. Most companies are required to file annual reports with the SEC, including forms 10-K and 20-F. The tax ID number is listed on the first page of these forms.

Contact the Department of Revenue of the state in which the LLC is registered. The Department of Revenue manages the taxable activity of LLCs, and retains copies of company tax forms. This information can be used to determine the tax ID number for the LLC.

Look in box 15 of Form W-2 issued by the LLC if you are or have been an employee of the company. LLCs are required by law to include their TIN on the W-2 form for employee tax purposes.

Contact the company directly. The human resources department should be able to provide you with the tax ID number, or send a copy of a company invoice containing the TIN to you.

Enlist the help of a private tax ID number locating service such as KnowX. Although you will generally have to pay a fee for this service, it can be worth it for hard-to-find TINs. These services can be useful for finding TINs for single-member LLCs.


Use paid services only as a last resort, as company TINs are generally public domain and freely accessible.