What’s the difference between a prenuptial agreement and a post-nuptial agreement? In this video, we break down how these two legal tools work and why the timing matters. A prenuptial agreement (prenup) is a legally binding contract signed before marriage, allowing future spouses to decide how their separate property, community property, income, retirement, and financial obligations will be handled once they are married. Prenups also give couples the freedom to contract outside California’s standard community property laws.