Post-Marital Agreements

Most people have heard of a prenuptial agreement. Fewer know that couples can enter into a similar agreement after they are already married. These are called postnuptial agreements — or post-marital agreements — and they serve many of the same purposes as a prenup. But they come with a set of legal and practical complications that prenups do not, and understanding those differences matters before you decide to pursue one.

The Key Legal Difference: No Statutory Framework

Prenuptial agreements in California are governed by the Uniform Premarital Agreement Act, codified in the Family Code. There is a clear statutory framework that tells attorneys, clients, and courts exactly what is required for a prenup to be valid and enforceable.

Postnuptial agreements have no equivalent statutory framework in California. They exist in a more legally ambiguous space, which means the standards for enforceability are less predictable and the risk of a court setting the agreement aside is meaningfully higher.

Fiduciary Duties Change Everything

When you get married in California, you and your spouse owe each other fiduciary duties. That is not a formality — it is a legal standard that applies to every financial transaction between spouses, including the negotiation and signing of a postnuptial agreement.

This is the central reason postnuptial agreements are more complicated than prenups. Before marriage, parties are dealing at something closer to arm's length. After marriage, they are fiduciaries to each other. Every postnuptial negotiation takes place in that context, and attorneys on both sides have to take it seriously.

What does that mean practically? It means both parties need full, transparent financial disclosure. It means neither party can be pressured, misled, or left without adequate time and information to make a genuinely informed decision. And it means that attempting to streamline or shortcut the process creates real legal risk for the agreement and potential malpractice exposure for the attorneys involved.

Why Couples Pursue Postnups

The reasons couples want postnuptial agreements are usually one of the following:

To rebalance a financial inequity. One spouse may have significantly more separate property wealth than the other, and both parties want to transmute some of that separate property to community property to create a greater sense of shared financial stake in the marriage. A common example is adding a spouse's name to the deed of a home purchased before the marriage.

To strengthen a marriage under strain. Some couples going through a difficult period believe that restructuring their finances more equitably will reduce tension and reinforce their commitment to each other. The postnup serves as a kind of financial reset.

To create a pre-negotiated framework. Sometimes couples want to agree in advance on how their assets would be divided if the marriage were to end, on terms they both consider fair now, before the emotional intensity of a divorce makes negotiation harder.

All of these are legitimate reasons. But they also illustrate why postnuptial agreements require careful handling: the same document that is meant to strengthen a marriage can look, in hindsight, like preparation for a divorce.

The Hidden Risk: Undisclosed Intent

One of the more challenging scenarios in postnuptial practice is when both parties present as wanting to strengthen their marriage, but one of them privately intends to use the agreement as a stepping stone to divorce. The agreement is negotiated in apparent good faith, signed, and then shortly afterward one spouse files.

Courts are aware of this dynamic. An agreement negotiated under the banner of reconciliation, where one party had an undisclosed intention to divorce, faces a real risk of being set aside. Drafting postnuptial agreements in a way that accounts for this risk — through strong disclosure provisions, independent counsel requirements, and clear recitals about the parties' intent — is part of what makes these agreements defensible.

What This Means for You

If you are considering a postnuptial agreement, here is what you should know going in.

It will take longer and cost more than a prenup. The fiduciary duty framework requires more rigorous process, more documentation, and more careful attention to disclosure and informed consent on both sides.

Both parties need independent counsel. This is not optional. An attorney who represents both spouses in a postnuptial negotiation is walking into a conflict of interest that can undermine the agreement entirely.

Full financial disclosure is mandatory. Both parties need to understand what they are agreeing to, what rights they are giving up, and what the realistic alternatives are.

The goal matters. A postnuptial agreement negotiated with genuine mutual intent to clarify finances and strengthen a marriage is in a very different legal position than one negotiated while one party is already planning an exit. The recitals and process surrounding the agreement should reflect the actual purpose.

Done carefully, postnuptial agreements can be valuable and enforceable. Done carelessly, they can give a false sense of security and fall apart exactly when they are needed most.