Delaware pioneered the Series LLC. It’s an LLC that can have different series within one LLC entity. In August 2005, IL approved a similar statute.
Once the bugs are worked out, a Series LLC may be the perfect vehicle for real estate investors. Each property could be put in a different Series. There would be only one filing fee for the Series LLC and the client would not have the cost and hassle of multiple LLCs to hold title to multiple properties.
One commentator does not recommend using Series LLCs in IL yet.
The IL statute says that if the correct filings are done with the state:
"then the debts, liabilities and obligations incurred, contracted for or otherwise existing with respect to a particular series shall be enforceable against the assets of such series only, and not against the assets of the limited liability company generally or any other series thereof…"
Here is the link to the IL statute.