According to papers obtained by PEOPLE, the actress is nearly five months behind on the mortgage payments for her Beverly Hills home, leaving her $100,000 delinquent.
The lender has placed the property in foreclosure, meaning Barton risks losing the estate unless she works out an agreement or gets current on her payments soon.
For the last few years, Barton has been splitting time between London and and her L.A. property – an eight-bedroom house TMZ says is worth over $8 million. In 2009, the actress took out a loan for $4.2 million on the home.
Once a Hollywood It Girl while starring on The O.C. from 2003-2006, Barton hit a couple of highly publicized roadblocks when she was arrested for DUI in December 2007, and then 18 months later when she was hospitalized on a psychiatric hold, which she called "a full-on breakdown" when talking to PEOPLE last year. "It was terrifying," she recalled. "Straight out of Girl, Interrupted. Story of my life."
With several recent acting roles in small films, including Throwdown and Hope Lost, Barton had seemed on a possible comeback, saying, "I've learned a lot. I'm stronger now, and I'm excited for what's ahead."
Calls to Mischa Barton's management were not returned.