Liza Minnelli is suing her estranged husband for at least $2m (£1.1m), alleging he stole from her during their marriage, US press reports say.
The couple married in March 2002
The Cabaret star has filed the lawsuit in New York, according to newspapers reporting The Smoking Gun website.
Gest, 50, has denied allegations over his business practices during his time acting as her agent and producer.
He has already filed a $10m (£5.m) lawsuit against Minnelli, 57, accusing her of abusing him.
He alleges she beat him during "drunken rages", leaving him needing medication for severe headaches and nausea.
Minnelli said these claims were "without merit".
The pair wed at a lavish ceremony in March 2002, attended by the likes of Michael Jackson and Elizabeth Taylor, but split after 16 months.
Following the announcement of their separation, they said there were no plans for divorce.
But their relationship has broken down into a bitter battle with both sides having now filed for divorce.
Minnelli's reported legal action questions Gest's expense deductions from money she earned from showbusiness after he became involved in her business affairs.
It alleges he denied her representatives access to financial records.
But Gest's lawyer, Raoul Felder, contends Gest "laid out millions of dollars" to produce her shows and has lost thousands of dollars.