BOSTON — State regulators are ordering Massachusetts utilities to lower their rates to reflect the reduction in the federal corporate tax rate approved by Congress.

The Department of Public Utilities on Friday instructed the utilities to account for any revenues associated with the difference between the previous and current federal corporate tax rates.

The agency also ordered the utilities to submit by May 1 their proposals to lower their rates to incorporate the reduction in the federal corporate tax rate.

Democratic Attorney General Maura Healey called the DPU decision “a huge victory for ratepayers” and said the agency had agreed with her office that all utility companies in Massachusetts must use the corporate savings from this federal tax bill to lower rates for customers.

Eversource had already agreed to lower their rates.