“Premarital agreements (FC 1610) are agreements that prospective spouses make in contemplation of marriage that are effective upon marriage, they require no consideration, and there is no fiduciary relationship between the parties because they are not yet married.
Premarital agreements executed from 2002 to the present (FC 1612(c) & FC 1615(c)) provide that there is a rebuttable presumption that the agreements were not entered into voluntarily unless the party against whom enforcement was sought was represented by independent legal counsel or expressly waived in writing, had not less than 7 calendar days to seek independent legal counsel, if unrepresented, was fully informed of the terms and basic effect of the agreement, was not executed under duress, fraud or undue influence, and was not entered into voluntarily by factors the court deems relevant.
Postmarital agreements are contracts made by and between spouses during the marriage, are not construed and enforced under the same standards as premarital agreements, have a fiduciary relationship between the spouses in postmarital agreements, and are often executed to change separate property into community property or vice versa.
Marital settlement agreements are the most common type of marital agreements, they memorialize the facts and issues that are undisputed or have been agreed upon, they are contracts and the laws regarding contracts apply, and there is no judicial form so must family law firms have their own version (template).”
[LW Greenberg, California Family Law]