Forming a series LLC in Illinois in 2026. Illinois authorises series LLCs under 805 ILCS 180/37-40 (Illinois LLC Act, series provisions). This guide covers the statutory framework, formation cost, how series are created, Illinois-specific tax and banking notes, and where Illinois series LLCs fit relative to Delaware and Texas — the two largest series jurisdictions.
Illinois's series LLC framework is codified at 805 ILCS 180/37-40 (Illinois LLC Act, series provisions). Illinois recognises series LLCs and each series can hold real estate or operating assets separately. Illinois banks are more comfortable with Illinois series LLCs than out-of-state banks tend to be.
A Illinois series LLC consists of a master LLC plus one or more series. Each series can hold its own assets, take on its own debts, and contract in its own name. Series are typically created internally in the operating agreement; some states require an additional public filing per series. Each series should maintain separate books and records to preserve the inter-series liability shield.
Cost: $150 Articles of Organization + $50 Certificate of Designation per series at the time of formation. $75 annual report for the master LLC.. Timeline: Illinois processes filings in 1-5 business days. End-to-end Anonymousllc.co series LLC formation in Illinois averages 5-10 business days including operating agreement drafting, EIN, and partner bank applications. Anonymousllc.co flat formation rate $397 + state fees as listed.
For federal tax, IRS Proposed Reg §301.7701-1(a)(5) (2010) treats each series as a separate entity. Most Illinois series LLCs file separate tax returns per series (typically Form 1065 partnership returns or Schedule C disregarded-entity treatment). For state tax, Illinois generally follows federal treatment but check Anonymousllc.co's /series-llc/tax-treatment/ guide for the up-to-date position.
Banking is the practical pain point for series LLCs. Mercury, Relay, and Bluevine open accounts for Illinois series LLCs with extra documentation (Certificate of Designation or equivalent + operating agreement language showing the series). Anonymousllc.co submits applications to 4-5 partner banks in parallel; series LLC approval averages 10-14 days.
Before forming a Illinois series LLC, consider whether two or three standalone LLCs would serve you better. Series LLCs win on filing-cost economics when you operate four or more separate entities and on liability segregation when you hold distinct assets (real estate, IP). They lose on bank acceptance, multi-state operations (states without series statutes may not recognise the inter-series liability shield), and tax-prep simplicity. Anonymousllc.co's intake will steer you to the simpler structure when it fits.
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