He faces up to ten years in prison and a €1m fine.
At the time, Fillon called the case a "political assassination" and remained in the presidential race despite the investigation - dubbed PenelopeGate - but his image was seriously damaged.
Former politician, Marc Joulaud, is also facing trial for misuse of public funds after he allegedly gave Penelope Fillon a fake job as an aide from 2002 to 2007, while her husband was a government minister.
She is alleged to have earned £113,400 in 2012-13 as a consultant for a literary magazine owned by a friend of her husband - a job which has also been alleged to be fake.
The magazine owner, Marc de Lacharriere, pleaded guilty and was given a suspended eight-month prison sentence and a £314,900 fine in 2018.
The trial on Monday was quickly suspended due to a lawyer's strike over President Macron's controversial pension reform.
Fillon served as prime minister under president Nicolas Sarkozy from 2007 to 2012.
He was also a government official under two previous presidents - Francois Mitterand and Jacques Chirac.
He now works for an asset management company and said last month he will not try to reenter politics.