British Gas owner Centrica has announced plans to cut 5,000 jobs this year as the company tries to set a new course.
Centrica said it would strip out three layers of management to slimline the business and cut down on bureaucracy.
Around half of the 5,000 lost jobs will be among the company's leadership, management and corporate staff.
It includes half of the 40-strong senior leadership team who will step down by the end of August.
Most of the restructuring is expected to happen in the second half of this year, the business said.
Centrica has been in decline for several years, having lost half of its earnings in the last decade as smaller energy suppliers have taken customers from British Gas.
The need to restructure has in part been accelerated by the impact of coronavirus.
Chief executive Chris O'Shea said: "Since becoming chief executive almost three months ago, I've focused on navigating the company through the Covid-19 crisis and identifying what needs to change in Centrica.
"We've learnt through the crisis that we can be agile and responsive in the most difficult conditions and put our customers at the heart of our decision making."
He added: "I truly regret that these difficult decisions will have to be made and understand the impact on the colleagues who will leave us. However, the changes we are proposing to make are designed to arrest our decline, allow us to focus on our customers and create a sustainable company."
