Legal Question in Family Law in California

Your premise is incorrect. When a couple buys property with a loan, they are not agreeing to be equally financially responsible for the debt. All they are doing is agreeing with the LENDER that they are both JOINTLY liable for the debt. All income during the marriage is community property, so any informal agreement about whose paycheck will pay what share of the loan is not legally binding. Only if the couple enters into a valid binding post-nuptial agreement on allocation of both the asset purchased, and the debt financing it, would a court do anything but divide both the asset and any remaining balance owed 50/50. The only exception is if one of the people puts pre-marriage money or assets (or other non-community property assets such as gifts or inheritance) into the purchase AND can show that the parties intended it to retain its separate property status, rather than just being a donation to the marital community property.