I just recently setup a LLC in a state which allows for the creation of Series LLC's. When doing my research, the Operating Agreement kept popping up as the most important thing to conceder and put in place. Especially for Series LLC's. There used to be a thread here in BHW, years back which covered the creation of a custom Operating Agreement - but the info is no longer available. The article over here goes into detail on the basic that need to be covered in a Series Operating Agreement. I know you can write your own, what I can't remember is if it needs to be written in a specific way: legalese or if it can be written in plain English. Before anyone jumps in and makes the wrong assumptions, my series LLC will not be trading in the USA (not even based there), it will not be doing any trading or making any income, it will only be a holdings company. Before anyone even asks why I even set it up or why I set it up where I did, the answer is: the cost is cheaper than in other countries for a series company, and it's not in a tax haven.