Maine's public benefits fund for energy efficiency was authorized originally in 1997 by the state's electric industry restructuring legislation. Under the initial arrangement, the administration of certain efficiency programs was divided among the State Planning Office (SPO), the state's electric utilities, and the Maine Public Utilities Commission (PUC). However, as a result of the 2002 legislative amendments, the authority to develop energy efficiency programs was effectively transferred from the SPO to the PUC, and the authority to implement these programs was transferred from the state's electric utilities to the PUC.

In 2009, the Act Regarding Maine's Energy Future (Public Law 372) established a new entity, the Efficiency Maine Trust, which became responsible for Maine's energy efficiency and renewable energy programs. All of the funds were transferred to the Efficiency Maine Trust July 1, 2010.* The Efficiency Maine Trust is governed by the independent Efficiency Maine Trust Board with oversight from the PUC. Public Law 637 of 2012 provided additional budget oversight to the Legislature, requiring the Efficiency Maine Trust to provide reports to the Legislature twice per year on the status of the fund's budget and programs. 

By statute, at least 10% of funds must support energy programs for low-income residents, and at least 10% of funds must support energy programs for small business customers. Prior to July 2015, the PUC assessed utilities to collect funds for energy programs and administrative costs; the fixed amount of the assessment is 0.145 cents per kilowatt-hour (1.45 mills/kWh). This fixed system benefit charge was replaced by a cap on the total amount utilities can collect through rates to fund energy efficiency resources. This cap is 4% of total retail electricity and transmission and distribution sales in the state.

There is no expiration date for the fund. In general, Efficiency Maine supports improvements in lighting efficiency, reductions in peak demand, high-performance buildings, appliance replacements, energy training and certification, and public education.  The Efficiency Maine Trust's funding includes money collected from the Regional Green House Gas Initiative, renewable portfolio standard alternative compliance payments, and grants, such as those received from the federal government's American Recovery Reinvestment Act (ARRA) in 2010. In FY 2015 and FY 2016, the Trust is also received Maine Yankee settlement funds.

The Efficiency Maine Annual Reports include additional details on the fund and the types of projects funded.

*In addition, Public Law 655 (2010) mandates that state revenue generated from energy corridor development on state-owned land would be deposited to the Efficiency Maine Trust (80%) and a new Transportation Efficiency Fund (20%).