An operating agreement is an agreement among limited liability company (LLC) Members governing the LLC's business, and Member's financial and managerial rights and duties. Many states in the United States require an LLC to have an Operating Agreement.LLCs operating without an Operating Agreement are governed by the State's default rules contained in the relevant statute and developed through state court decisions.An Operating Agreement is similar in function to corporate by-laws, or analogous to a partnership agreement in multi member LLC's.LCs operating without an Operating Agreement are governed by the State's default rules contained in the relevant statute and developed through state court decisions. An Operating Agreement is similar in function to corporate by-laws, or analogous to a partnership agreement in multi member LLC's.