Belgarath, I will assume that by "one person LLC" you mean the tax-exempt org owns all of the interests in these LLCs. Assuming that, under Treas. Reg. 301.7701-2(a)the LLCs are treated the same as a division of the tax-exempt org for income tax purposes. 457(b) is an income tax section. None of that is common sense, but based on it I would go with your common sense. Get the LLCs to sign up all the paperwork, however, since that is not entirely a Federal income tax issue.