Open Access Transmission Service (OATT) and Functional Unbundling

Order 888 established the foundational framework for open, non-discriminatory access to electric transmission systems across the United States. It required all public utilities that own, control, or operate interstate transmission facilities to offer comparable, non-discriminatory transmission service to wholesale electricity buyers and sellers under a pro forma Open Access Transmission Tariff (OATT). The order required functional unbundling of transmission from generation and wholesale power functions, and it defined firm and non-firm point-to-point and network integration transmission service alongside a framework for stranded-cost recovery. Companion Order No. 889 addressed OASIS posting and Standards of Conduct in greater detail. Order 888 fundamentally restructured the wholesale electricity market by separating generation and transmission services and preventing utilities from favoring their own generation affiliates over competitors.