A limited liability company’s operating agreement or company agreement is similar to a corporation’s shareholder agreement, and provides for the management of the LLC, and the rights and duties of the owners of the LLC (members) and the managers of the LLC, if any.

Specifically, the LLC operating agreement should address the company’s finances, capital contributions, percentages of ownership, voting rights, meetings, notices, buyouts, distribution of profits and losses, officers, and other matters. Limited liability companies generally may be managed by the members or by appointed or elected managers.

In Illinois, a limited liability company (LLC) is governed by the Illinois Limited Liability Company Act. The operating agreement is a key document for an LLC as it outlines the company's structure and the rules for its operation. While not required by law, it is highly recommended to have an operating agreement to provide clear guidance on the management of the LLC, the rights and duties of members, and procedures for handling various business matters. The operating agreement should address financial management, including capital contributions and distribution of profits and losses; ownership interests, detailing members' percentages of ownership; voting rights and procedures; rules for meetings and notices; processes for buyouts and transfers of membership interest; and the designation of officers and managers, if management is not member-operated. Illinois law allows LLCs to be managed by its members (member-managed) or by one or more managers (manager-managed), and the operating agreement should clearly state the chosen management structure.