Massachusetts utilities should give ratepayers the $40 million they saved in federal taxes in the first half of 2018, the state attorney general said.

Attorney General Maura Healey (D) urged the Department of Public Utilities in a March 7 motion to reverse its Feb. 15 ruling that allowed electric, gas, and water companies to keep the savings they reaped between Jan. 1, 2018, and June 30, 2018, as a result of the 2017 federal tax overhaul.

  • The federal tax law reduced the corporate tax rate to 21 percent from 35 percent.
  • Starting in June 2018, the utilities reduced their rates to reflect the federal tax savings.
  • National Grid Plc and Eversource Energy, which each deliver electricity and natural gas in Massachusetts, are potentially impacted. The companies didn’t immediately respond to requests for comment.
  • The department said there is no deadline by which it must deny or allow the motion.