Supermarket chain heir Xavier Kemlin launched the highly unusual criminal complaint at a court in central French city of Saint-Étienne.
A judge has now ruled that Ms Trierweiler, president François Hollande’s live-in girlfriend, can be charged and could face trial as early as September.
Officials figures from the prime minister’s office revealed last month that Ms Trierweiler’s five staff at the Elysée Palace cost the state £16,000 a month – half the £30,000 per month cost of Carla Bruni’s eight assistants during her time as first lady.
Mr Kemlin told French newspapers: “I find it absolutely scandalous that our taxes are being used to house, feed, upkeep and pay for the staff and travel of a lady to whom we have no legal obligation.”
He branded Ms Trierweiler the “president’s mistress” and accused the couple of not getting married to avoid France’s wealth tax, which applies to the assets of married couples.
Mr Kemlin is the great-grandson of Geoffroy Guichard, founder of the Casino supermarket chain, and has lived in Switzerland since he was 16.
He added: “She comes from a family of bankers. It’s a question of morality.
“She should either marry or form a legal civil union and become a proper first lady, or stop spending our money.”
Mr Kemlin’s lawyer André Buffard asked Le Figaro newspaper: “If President Hollande can’t make a commitment to a woman, how can he make one to the French people?”
Ms Trierweiler was also criticised by outspoken French MP Bernard Debré in December when he wrote in his blog that the president’s partner should “stop meddling in the country’s affairs”.
He wrote: “Mme Trier-weiler, self-proclaimed first lady, is nothing more than the president’s mistress. What is she meddling in? What right does she have to speak out?
“When one is in her position, after the blunders she has already made, it would be much better if she shut up.”
The 68-year-old MP for Paris also said her job as a journalist was “incompatible” with her role as the president’s partner.
He added: “She might well want to get into politics, but she should stop being a journalist and define her position at the Elysée Palace.”
Ms Trierweiler, 47, a divorcee, has been the target of repeated media attacks since Mr Hollande was elected president in May last year.
She was at the centre of accusations she tried to wreck the career of Segolène Royal – the mother of Mr Hollande’s four children – by tweeting her support for a candidate standing against her in the parliamentary elections.
Ms Royal lost the election and later said she had been “stabbed in the back” by Mr Hollande’s girlfriend.
Ms Trierweiler also faced humiliation last month when her boss at the French magazine where she works said that she would be sacked at the end of this year.
Paris Match’s owner Arnaud Lagardère described her as “an unpinned grenade” who had caused him “nothing but trouble” and said that he would not be renewing her contract in January “to avoid any conflict of interest”.
In a book about Ms Trierweiler called Between Two Fires, written by investigative journalist Anna Cabana, the president’s girlfriend is described as “a cocktail of jealousy, vengeance and political calculation”.
Another book, The Favourite, by journalist Laurent Greilsamer, says of Ms Trierweiler: “As I see it, you have shown yourself to be not normal, snooty, infatuated, explosive, unpredictable. And visibly dangerous.”