A post-nuptial agreement is essentially identical to prenuptial, or prenup, except that it is an agreement between spouses instead of fiancés. If the document is written up properly, prenuptial and postnuptial agreements can be a massive help to just about any couple. These agreements are not just for the very wealthy anymore. With a prenup, fiancés can discuss their finances and goals heading into a marriage, and outline the financial steps they will take to reach them, such as supporting a spouse through school. These agreements can also detail what would happen to property in the event of divorce or death.