"Their finances are separate, but they don't keep secrets from each other, and when it comes to things for the kids, the house they're working on, they share expenses," a source tells PEOPLE in this week's issue.
For more from Kim and Kanye – including their separate finances, lavish home plans and what Kim thinks about her husband's Twitter drama – pick up this week's issue of PEOPLE, on newsstands Friday
"She feels good that she has her own money if things ever go south, but of course it stresses her out a little that they even have to think about finances at all," says the source.
Forbes estimated Kardashian's 2015 earnings at nearly $53 million and West's in 2014 at $20 million. On Saturday, West tweeted he has $53 million in "personal debt," later clarifying his remarks, saying he "personally rich" but needs "access to more money in order to bring more beautiful ideas to the world."