Le Pen, who had refused to respond to previous summonses, was questioned and charged on Friday afternoon.
She intends to appeal invoking parliamentary immunity on Monday, according to her lawyer, Rodolphe Bosselut.
Le Pen, who won a seat in the French National Assembly for the first time in this month's election, was elected to the European parliament in 2004.
She was charged with breach of trust in relation to the employment of her chief of staff, Catherine Griset, and her bodyguard, Thierry Légier, between 2009 and 2014.
As National Front president, she was also charged with complicity in breach of trust in relation to alleged abuse of European parliamentary funds by other FN MEPs.
She read a declaration to the investigators but invoked her right to remain silent and refused to answer their questions.
The European parliament estimates that the alleged abuse cost it five million euros in 2012-17.
Some of the money was being stopped out of Le Pen's salary as an MEP.