The equivalent of a prenuptial agreement for couples in some states and in the U.K. that allow registration as domestic partners or civil union partners. That is, it is a substitute for a prenuptial agreement when parties only seek a civil union. See SBP Law. As a prenuptial agreement, the purpose is for the couple to determine how to regulate their finances during the union, and how to divide their assets in the event of a dissolution of the union.
[Last updated in September of 2020 by the Wex Definitions Team]