The man at the head of Northern Ireland's Utility Regulator is to step down from his role at the end of October.
Shane Lynch has been chief executive of the organisation for five years and said he plans to leave at the end of October.
The regulator is currently embroiled in a battle with NIE over a disagreement on RP5, the five-year price control period which sets out how much NIE can charge consumers and how much it can invest in infrastructure.
It was meant to begin in April 2012 but has been delayed as the argument, which is now in the hands of the competition commission, runs on.
"Before my departure, I hope to have substantially delivered on making a full contribution to the Competition Commission's determination of the NIE price control," Mr Lynch said.