Brad Pitt and Angelina Jolie, who remain unmarried in real life, will play husband and wife in a new film.
Pitt, 50, is likely to receive a lesser fee than his wife who wrote the movie and will direct it, according to the Hollywood Reporter.
By the Sea has been described as an "intimate, character-driven drama" by Universal Pictures.
Speaking to Extra TV earlier this year Jolie, 39, said: "It's not a big movie, not an action movie. It's the kind of movie we love but aren't often cast in. It's a very experimental, independent type film where we get to be actors together and be really raw, open, try things."
It is the couple's first film together since Mr & Mrs Smith in 2005 which led to their off-screen romance.
Pitt has said the couple, who have six children together, would not marry until same-sex marriage is legalised throughout the US and "everyone in this country had the right to get married". Jolie has said she intends to do less acting and focus on work behind the camera and her role with the United Nations.
Universal Pictures co-chairman Donna Langley said the couple were two of Hollywood's brightest talents "and we are excited to be a part of their collaboration on this powerful piece".