How Do I Get an Illinois State ID Number for an LLC Company?

By Tom Speranza, J.D.

How Do I Get an Illinois State ID Number for an LLC Company?

By Tom Speranza, J.D.

If you have a limited liability company (LLC) that conducts business in Illinois or has employees based there, you must register with the Illinois Department of Revenue to obtain an Illinois tax identification number. This ID number facilitates your company's payment of Illinois income, sales and use taxes, as well as the amounts withheld from employee wages for things such as Illinois individual income tax and unemployment insurance.

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Illinois issues the ID number based on the information you enter on Form REG-1, but certain businesses that pay specialized kinds of taxes (cigarette, liquor, telecommunications, etc.) are required to file additional schedules.

Domestic vs. Foreign LLCs

Before you apply for an Illinois state ID, you first need an LLC formed in Illinois or an LLC formed in another state (a so-called foreign LLC) that has qualified to do business in Illinois.

  • To form an Illinois LLC, file articles of organization on Form LLC-5.5 with the Illinois Secretary of State.
  • To qualify a foreign LLC in Illinois, file an Application for Admission to Transact Business on Form LLC-45.5 with the Illinois Secretary of State.

Although the state provides some handy online resources to assist small business owners with forming and qualifying LLCs, things can get tricky if your LLC has a complicated capital structure or if you run into trouble reserving a name. For example, if your LLC formed in another state but its name is not available in Illinois, you'll need to use a different name in certain situations. A corporate lawyer experienced with the Illinois law can advise you.

Conducting Business in Illinois

Illinois law does not provide an exact definition regarding what constitutes doing business in Illinois, but, as a general rule, having a physical presence in Illinois (such as an office, store, or warehouse) qualifies as conducting business there. Having employees of the LLC located in Illinois also triggers the registration requirement.

Illinois law does say that certain activities DO NOT rise to the level of transacting business, including:

  • Commencing or defending a lawsuit in an Illinois court
  • Having accounts in Illinois banks
  • Selling products or services using independent contractors located in Illinois
  • Having a corporate officer or director who lives in Illinois
  • An occasional, isolated business transaction in Illinois

The rules get more complicated if you have an online business that sells services or ships goods to Illinois customers. Your company's accountant or lawyer can help you determine whether your online activities require you to register your foreign LLC in Illinois.

Information Required on Form REG-1

The Form REG-1 requires some detailed information about your LLC. You can complete the form online or print out a paper copy. Most of the required information appears in your LLC's articles of organization and operating agreement and your tax return:

  • Federal tax identification number
  • Official entity name
  • Fictitious or "doing business as" name (DBA)
  • Addresses from which the LLC does business in Illinois
  • LLC owners and officers (which can be the same people if the LLC is member-managed; if your LLC has managers, they would be considered officers for purposes of the form)
  • The nature of the LLC's business and its products or services
  • Whether the LLC has Illinois-based employees

If your company regularly operates in Illinois or employs people who live there, you'll need to obtain an Illinois tax ID number. This ID number is necessary for paying the taxes associated with doing business and paying employees in the state, and you must submit at least one form in order to get it.

This portion of the site is for informational purposes only. The content is not legal advice. The statements and opinions are the expression of author, not LegalZoom, and have not been evaluated by LegalZoom for accuracy, completeness, or changes in the law.