Victorian independent MP Geoff Shaw has been charged with 23 offences.
The Liberal turned independent had been the subject of a misconduct in public office investigation and holds the balance of power in the state's parliament.
Police say the charges relate to allegations of misconduct in public office by a serving member of the Victorian Parliament in 2011.
"Victoria Police has charged a 45-year-old Frankston man with 23 charges of obtain financial advantage by deception and one count of misconduct in public office," a police statement said.
Shaw has been summonsed to appear at Melbourne Magistrates Court on October 8.
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His electorate office had no immediate comment and referred calls to a media manager.
Shaw had been under investigation after the state ombudsman found he had used his taxpayer-funded car for his hardware business.
He also used a parliamentary fuel card to pay for petrol for another private vehicle, leading the ombudsman to find Shaw might be in contempt of parliament or have breached parliamentary privilege.
The state parliament privileges committee grilled him last Thursday over the ombudsman's findings.
The committee can recommend to parliament that he be reprimanded, suspended or removed from parliament.
Shaw was seen entering state parliament on Tuesday for a sitting day but has not yet made any comment on the charges.
Shaw last week said he repaid $1250 over the misuse of his taxpayer-funded vehicle as a gesture of goodwill.
"This was an offer that I made on the day these allegations arose, and again to the ombudsman, who noted it in his report," he said.
But opposition scrutiny of government spokesman Martin Pakula criticised the Frankston MP for acting like he had done Victorians a favour by repaying the money rather than admit he's done wrong.
Earlier on Tuesday Premier Denis Napthine said Shaw's decision to pay back the money was the "responsible thing to do", but having him return to the Liberal party was not on the agenda.
"There has been no discussions and no proposals for Geoff Shaw to return to the parliamentary Liberal Party," Dr Napthine said on Tuesday morning, before the charges against Shaw were announced.
