LLC Tax Filing Requirements in Illinois

How an LLC Is Taxed by Default

An LLC (limited liability company) is a legal business structure, not a tax classification. By default, the IRS treats a single-member LLC as a "disregarded entity" — its income and expenses are reported directly on the owner's personal tax return. A multi-member LLC is treated as a partnership by default, filing its own informational return and passing income through to the members.

Federal Filing Basics

A single-member LLC's business income and expenses typically flow onto the owner's Form 1040, usually on Schedule C. A multi-member LLC generally files Form 1065 (U.S. Return of Partnership Income), and each member receives a Schedule K-1 reporting their share of income to include on their personal return.

Illinois State Filing Requirements

Illinois follows the same default classification as the IRS. A single-member LLC's income is reported on the owner's Form IL-1040. A multi-member LLC generally files an Illinois partnership return (Form IL-1065) alongside the federal Form 1065.

Separate from income tax, every Illinois LLC must file an annual report with the Illinois Secretary of State to stay in good standing. This is a compliance filing, not a tax return, but missing it can put your LLC's status at risk.

Electing S-Corporation Tax Treatment

An LLC that meets IRS eligibility requirements can elect to be taxed as an S-corporation instead of its default classification. This changes how income is taxed and how much goes through payroll versus distributions. Whether it makes sense depends on your income level and how the business operates — it's worth a conversation before making the election, not after.

Common Mistakes

Forgetting the Illinois Secretary of State annual report, which is separate from any tax filing
Assuming a multi-member LLC doesn't need to file anything until members report income personally
Electing S-corp status without reviewing whether it actually helps, given the added payroll requirements
Mixing personal and business expenses, which makes accurate filing harder at year-end

This article is for general informational purposes and is not personalized tax or legal advice. Contact us directly to discuss your specific situation.