All of Maine's electric utilities -- investor-owned utilities (IOUs), consumer-owned utilities (COUs), which include municipal utilities and electric cooperatives -- must offer net energy billing for individual customers. Furthermore IOUs are required to offer net metering for shared ownership customers, while COUs may offer net metering to shared ownership customers at their discretion. "Shared ownership" allows for community net metering, where several people invest in an eligible system and are therefore allowed to benefit (see below for more information).