Energy business E.On is cutting up to 500 jobs at its head office in Coventry and at its centre near Nottingham.
The company said it was looking to reduce numbers to reflect the changed nature of the business following the sale of its distribution arm, Central Networks, in March.
E.On said it hoped to make the cuts through voluntary redundancies.
The company, which generates electricity and retails power and gas, employs 12,000 people in the UK.
The chief executive of E.On UK, Dr Paul Golby, said: "We had to undertake a deep and rigorous review of how much money we spend in order to ensure we keep costs as low as possible for our customers.
"While I'm very aware that this will be a difficult time for our colleagues, it is our aim to keep uncertainty to a minimum and to achieve these redundancies by voluntary means."
E.On said that because of the voluntary nature of the planned redundancies, it is currently not possible to say how many people at each site will be affected by the changes.