Patricia Cahuzac was charged in connection with with the scandal that cost her husband, the disgraced former budget minister Jerome Cahuzac his job, a judicial the source said.
The dermatologist and her husband, a former plastic surgeon, ran a flourishing hair transplant salon in Paris. Jerome Cahuzac also served as an adviser to several pharmaceutical companies.
The ex-minister, whose tasks in Socialist President Francois Hollande's cabinet included battling tax fraud, initially denied allegations by French investigative news website Mediapart that he had funds in a Swiss bank account.
But he did a U-turn when prosecutors opened an official probe into the undeclared overseas account said to contain around €600,000 euros ($770,000).
He resigned on March 19th and has admitted to having the account for about two decades, in a scandal that dealt a major blow to Hollande's government.
Earlier this month, Pierre Condamin-Gerbier, a key witness in the tax fraud investigation, was placed under arrest in Switzerland after breaching the country's banking secrecy laws by testifying in the Cahuzac investigation.
In recent months France has made a special effort to crack down on tax evaders, with a focus on French nationals who inherit from wealthy Swiss residents.