The state's crime and corruption watchdog has charged an employee and contractor at WA energy supplier Horizon Power with 78 offences.
Horizon said it reported suspected misconduct to the CCC last year, and had been cooperating with the investigation.
Police and CCC officers searched offices including Horizon's Perth headquarters, an accounting firm and residential addresses.
A 42-year-old man from Salter Point and a 46-year-old man from Mt Hawthorn were charged with 78 counts of an agent corruptly soliciting or receiving a reward.
Horizon supplies power to about 100,000 residents and 10,000 businesses across regional Western Australia.
The government-owned entity informed staff this week that an employee and contractor had been arrested and charged.
"Horizon Power can confirm that no customer data has been impacted by the alleged misconduct," the entity said in a statement to the ABC.
The statement said it could not confirm any further details as the investigation was ongoing.
Last year the company was accused of overcharging customers for power in the state's Kimberley and Pilbara.
A spokeswoman for Horizon said there was no link between those issues and the current inquiry.
She also said the problems with incorrect charges had been resolved, with one incident in Broome that affected more than 1,000 customers blamed on an issue with the manual reading of meters.
The spokeswoman said in 2016, Horizon completed a program of exchanging all electricity meters to advanced meters which would prevent a repeat of the issue.
In 2014-15 Horizon spent $156,357 on private investigators to examine public servants accused of wrongdoing.
