Massachusetts Gov. Maura Healey is urging three of the state’s largest utilities to issue transmission-rate refunds immediately, months before they are legally due, as households brace for winter energy bills. In a letter sent Tuesday, Oct. 13, to executives at Eversource, National Grid and Unitil, Healey asked the companies to stop pursuing an appeal and begin returning money to customers. She also sent the letter to the head of ISO New England, the region’s grid operator. The refunds follow a March decision by the Federal Energy Regulatory Commission that lowered the return on equity utilities can earn on transmission investments. The ruling initially set a 30-day refund deadline, but that date was later extended to May 20, 2027. The U.S. Court of Appeals for the D.C. Circuit rejected the utilities’ request to delay the matter further, according to Healey’s letter. About $1.5 billion is owed to electricity customers across New England. Healey’s letter did not specify how much of that total is attributable to Massachusetts customers. “Customers should not have to wait any longer for money that FERC has determined must be returned to them,” Healey wrote, calling for the utilities to end their appeal. She asked them to provide by Oct. 27 an accounting of the expected Massachusetts refunds, along with a timeline and explanation of how customers will receive the money. The push comes as energy affordability has become a prominent issue in the Massachusetts governor’s race. Healey is seeking reelection and is scheduled to debate Republican challenger Mike Minogue on Thursday. Before their first televised debate, she declared a state energy emergency and announced measures including one-time heating assistance for middle-income households, expanded aid for low-income households and a temporary pause on clean-energy charges on electric bills. Negotiations over broader energy-affordability legislation have remained in a private conference committee for months. House Speaker Ron Mariano has said lawmakers are not treating Election Day as a deadline for completing negotiations. Minogue’s campaign has proposed cutting state-mandated utility fees on his first day in office, saying they account for one-third of bills. His plan also calls for investment in natural-gas pipelines and consideration of modular nuclear power. Eversource CEO Joseph Nolan recently suggested that criticism of utilities by governors was partly shaped by the approaching election, according to CommonWealth Beacon. Speaking at an industry conference, Nolan said utility executives had good relationships with the governors, despite public criticism.