A postnuptial agreement is a written agreement executed after a couple gets married, or have entered a civil union, to settle the couple's affairs and assets in the event of a separation or divorce. It is normally "notarized" or acknowledged and is usually the subject of the statute of frauds. Like the contents of a prenuptial agreement, provisions vary widely but commonly includes provisions for division of property and spousal support in the event of divorce, death of one of the spouses, or breakup of marriage. In rare cases, a "prenup" may be enforceable even without a marriage, such as with a domestic partnership or registered partnership.
In the United States, as with prenuptial agreements, five additional elements are typically required for a valid postnuptial agreement:
Postnuptial agreements only came to be widely accepted in the United States in the latter half of the 20th century. For many years, US jurisprudence followed the notion that contracts, such as a postnuptial agreements, could not be valid when executed between a husband and wife. The inability of a husband and wife to contract with one another was due to the concept of marital unity: at the time of marriage, husband and wife become a single entity or person. Since one may not enter into a contract with one's self, a postnuptial agreement would be invalid. Even after the US courts began to reject marital unity as a legal theory, postnuptial agreements were rejected as being seen to encourage divorce.
It was only in the 1970s that postnuptial agreements were met with wide acceptance in the United States. The motivating factors considered to be behind this acceptance were the increase in divorce during the 1970s along with the implementation of so-called "no fault" divorces, granting divorces for any reason. Upon the wave of legislative and statutory changes, postnuptial agreements began to find acceptance in American jurisprudence.