Several other people, including a judge and Stephane Richard, now head of France Telecom, then head of Lagarde's office, have been accused of "conspiracy to commit fraud".
After four interrogations of Lagarde, including one yesterday, the committee of magistrates investigating the affair decided there was a prima facie case that she acted negligently in public office.
If charged and found guilty both far from certain Lagarde could face a one-year prison sentence and a 15,000 fine.
In an indignant statement, Lagarde said she would vigorously contest the "completely unfounded" allegations.
"After three years of investigation, and dozens of hours of questioning, the committee [of magistrates] has acknowledged that I was guilty of no fraud," she said.
"They have been reduced to accusing me of not being sufficiently vigilant." Independent