Brad Pitt and Angelina Jolie have signed a pre-nuptial agreement worth S$396,666,400 million.
The couple - who raise six children together - are planning to marry over Christmas.
The 'Moneyball' actor has had his lawyers draw up a 101-page document which states that, in the event of a split, he will keep his pre-marital £110 million fortune and his partner's £90 million assets will also be protected.
And the agreement also states the couple would share equal joint custody of their kids if they ever go their separate ways.
A source told Grazia UK magazine: "Angelina has always been a bit reluctant about having a pre-nup but Brad persuaded her it's for the best.
"He's a romantic guy, but also very practical, and given they're worth £200 million between them, with six children and a lot of property across the globe, it definitely makes sense.
"Both Brad and Angelina have been married before so they know how messy a divorce can get. It's even more important this time because there are children involved and Brad wants them to cover all eventualities.
"The couple can't legally marry in France as they are not residents of the country, but are planning a wedding blessing at their French home following a ceremony in Hawaii, Angelina's late mother Marcheline Bertrand's favourite place.
The source said: "Hawaii means that her mother can be a part of a small ceremony on her favourite beach. Then the main event will be a wintery-themed bash in France with all of their closest friends and family. Everyone, especially the children, is very excited.
"They love the idea of a Christmas wedding at their French home, Chateau Miraval, with a big roaring fire and lots of festive decorations."