A postnuptial agreement in California is a contract between spouses, signed during the marriage, that changes or confirms the character of their property as community or separate, and often addresses what happens to that property at divorce or death. California has no statute called a postnuptial agreement act. The Premarital Agreement Act does not apply once the couple is married. Instead, a California postnuptial agreement is governed by the transmutation statutes, Family Code §§ 850–853, and by the fiduciary duties spouses owe each other under Family Code § 721. As a California postnuptial agreement attorney, Michael Holmes drafts and reviews these agreements with those stricter rules in mind.
The scope of the practice matters here. In California, Holmes Law’s family law work is limited to marital agreements, meaning prenuptial and postnuptial agreements. Holmes Law does not handle California divorce, legal separation, custody, child support, spousal support or property division litigation, and does not negotiate marital settlement agreements for couples who are divorcing; Idaho is the only state where the practice offers full-service family law. Holmes Law is a remote practice with no physical office. This page goes deeper than the broader California marital agreements page, and a companion page covers California prenuptial agreements.
Why Couples Sign Postnuptial Agreements in California
Postnuptial agreements are signed for many of the same reasons as prenups, but the triggers are events that happen after the wedding:
- one spouse starts or buys into a business and wants it, or its growth, to be separate property, or the co-owners require spousal documentation as part of a buy-sell arrangement;
- one spouse receives or expects an inheritance and wants to confirm how it and its income will be treated;
- a couple who never signed a prenup wants certainty about property built up during the marriage;
- a couple wants to convert separate property into community property, for example to gain the income tax basis benefits of community property at death;
- a couple has moved to California from another state and wants to clarify how existing property will be treated;
- estate planning requires a clear record of which assets are community and which are separate before funding a trust.
Postnuptial Agreements Are Transmutations, Not Premarital Agreements
A common mistake is to treat a California postnuptial agreement as a prenup signed later. It is not. Family Code § 850 allows spouses, by agreement or transfer, to transmute community property to the separate property of either spouse, separate property of either spouse to community property, and the separate property of one spouse to the separate property of the other. Section 851 makes transmutations subject to the laws governing fraudulent transfers. Section 852 sets the formal requirements. Section 853 addresses statements in wills.
Because the Premarital Agreement Act does not apply, the specific § 1615(c) seven-day rules for premarital agreements do not govern a postnuptial agreement. That does not make postnuptial agreements easier to enforce. In several respects the standard is stricter, because spouses are fiduciaries of each other and because the writing requirement for transmutations is demanding.
The Express Declaration Requirement Under Family Code § 852
Under § 852(a), a transmutation of real or personal property is not valid unless it is made in writing by an express declaration that is made, joined in, consented to or accepted by the spouse whose interest in the property is adversely affected. California courts apply this requirement strictly:
- In Estate of MacDonald (1990) 51 Cal.3d 262, the California Supreme Court held that the writing must contain language that expressly states that the characterization or ownership of the property is being changed, and extrinsic evidence cannot be used to supply that intent. A spouse’s signature on a consent form for a retirement account beneficiary designation was not enough.
- In In re Marriage of Benson (2005) 36 Cal.4th 1096, the court held that the part performance doctrine does not excuse compliance with § 852. A spouse who acted on an oral agreement could not rely on that conduct to prove a transmutation.
- In In re Marriage of Valli (2014) 58 Cal.4th 1396, the court held that the transmutation rules apply to property acquired from a third party during marriage, not just transfers between spouses. Placing a life insurance policy in one spouse’s name did not transmute it without an express declaration.
For couples, the lesson is that informal arrangements, retitling assets, joint account designations and statements of intent are not reliable ways to change property character in California. The agreement must say clearly which property is being transmuted, from what character to what character, and it must be signed by the spouse whose interest is reduced.
Two other parts of § 852 are important. Under § 852(b), a transmutation of real property does not affect third parties without notice unless it is recorded. Under § 852(c), the express declaration requirement does not apply to gifts between spouses of clothing, jewelry or other tangible articles of a personal nature that are not substantial in value taking into account the circumstances of the marriage.
Fiduciary Duties Between Spouses and Undue Influence
Family Code § 721 provides that spouses occupy a confidential relationship and owe each other the highest good faith and fair dealing, and that neither may take unfair advantage of the other. This has major consequences for postnuptial agreements.
When a transaction between spouses gives one spouse an unfair advantage, a presumption of undue influence arises, and the advantaged spouse must prove the agreement was freely and voluntarily made with full knowledge of the facts and a complete understanding of its effect. In re Marriage of Haines (1995) 33 Cal.App.4th 277 applied this presumption to a transmutation. In re Marriage of Delaney (2003) 111 Cal.App.4th 991 describes how the presumption can be rebutted.
The presumption does not arise in every case. In In re Marriage of Burkle (2006) 139 Cal.App.4th 712, the court held that a postnuptial agreement negotiated by spouses who were each represented by counsel, which gave advantages to both of them, raised no presumption of undue influence. The practical takeaway is that a California postnuptial agreement is strongest when each spouse has independent counsel, the exchange runs both ways, the financial disclosure is complete, and the negotiation is documented.
Financial Disclosure
Because spouses are fiduciaries, full disclosure is not just good practice. It is part of the duty itself. Family Code § 721 incorporates duties of disclosure and access to information about community property, and a spouse who hides assets or misstates values risks having the agreement set aside. A California postnuptial agreement should attach schedules listing each spouse’s separate property, the community property, and any debts, with values or a method for valuing them, and each spouse should acknowledge receiving the information.
What a California Postnuptial Agreement Can Address
Within these rules, a postnuptial agreement can:
- transmute specific assets, such as a business interest, a home or an investment account, from community to separate property or the reverse;
- set rules for characterizing future earnings, business growth or income from separate property;
- waive or confirm reimbursement rights, including rights under Family Code § 2640 for separate property contributions to community property;
- address how the parties will treat property if they separate, with specific formulas rather than named assets that may lose value;
- coordinate property character with a California trust or will;
- document the character of property held by a revocable trust so the trust’s schedules and the spouses’ intent match.
A postnuptial agreement cannot adversely affect child support, and it cannot decide child custody, which a court decides based on the child’s best interests.
The Open Question on Spousal Support Waivers
Whether spouses can waive spousal support in a postnuptial agreement signed during an ongoing marriage, outside an immediate separation, is an open question in California. The spousal support rules in Family Code § 1612(c) apply by their terms to premarital agreements. No controlling appellate authority squarely holds that a mid-marriage support waiver is enforceable, and there are serious arguments against it. Holmes Law advises clients that any support provision in a California postnuptial agreement carries real enforceability risk, and drafts the property provisions so they stand on their own if the support provisions fail.
Estate Planning, Tax and Retirement Considerations
Postnuptial agreements are often part of a larger California estate planning project. Converting separate property to community property can allow both halves of the community property to receive an income tax basis adjustment at the first spouse’s death under Internal Revenue Code § 1014(b)(6), which can reduce capital gains tax for the surviving spouse. Converting community property to separate property can support a plan that leaves one spouse’s share to children from a prior marriage. Both directions have consequences at divorce as well as death, so each spouse needs to understand the trade-offs.
Family Code § 853 provides that a statement in a will about the character of property is not admissible as evidence of a transmutation in a proceeding commenced before the testator’s death. Couples who want to change property character should do so with a separate agreement, not a clause in their wills.
Federal law also limits what a postnuptial agreement can do with retirement plans. Waivers of survivor benefits in a qualified plan must meet federal consent rules and the plan’s own requirements, including a written consent witnessed by a notary or plan representative. A postnuptial agreement should require the spouses to sign the plan’s forms rather than rely on the agreement alone.
When a Postnuptial Agreement Is Not the Right Tool
A postnuptial agreement is a planning document for an ongoing marriage. If spouses have already decided to separate or divorce, the right document is usually a marital settlement agreement negotiated as part of a dissolution or legal separation. Holmes Law does not handle California divorces or marital settlement agreements, and a couple in that position should consult a California family law attorney who does.
How the Process Works With Holmes Law
A California postnuptial agreement engagement with Michael Holmes usually follows these steps:
- Initial consultation. Michael Holmes meets with the client spouse to understand the goals, the family’s property and the reason the agreement is being considered now.
- Characterization review. Before anything is transmuted, the current character of each asset is analyzed, including separate property brought into the marriage, commingled accounts, businesses and retirement assets. Many couples discover that their assumptions about what is separate and what is community were not accurate.
- Disclosure. Both spouses exchange complete financial information, which becomes the schedules attached to the agreement.
- Drafting and negotiation. Holmes Law prepares a draft with express transmutation language for each affected asset, and negotiates with the other spouse’s independent counsel.
- Signing and implementation. The spouses sign, real property transmutations are recorded where appropriate so they bind third parties, titles and beneficiary designations are updated, and the estate plan is conformed.
Giving the other spouse ample time to review the final draft is not a statutory seven-day requirement for postnuptial agreements, but it is strong evidence that the agreement was entered into freely and with full understanding, which is exactly what a court will examine if the presumption of undue influence arises.
Reviewing or Revising an Existing Agreement
Couples who already have a prenuptial or postnuptial agreement sometimes want to change it. Circumstances change: a business grows, children are born, an inheritance arrives or the couple moves to or from California. An amendment that changes the character of property is itself a transmutation and must meet the § 852 express declaration requirement. Holmes Law reviews existing agreements for compliance with the rules in effect when they were signed and advises whether an amendment or a new agreement is the better approach.
Frequently Asked Questions
Is a California postnuptial agreement enforceable?
Yes, if it meets the transmutation requirements of Family Code § 852, is free of undue influence under § 721, is supported by full disclosure, and does not violate public policy. Agreements negotiated with separate counsel for each spouse are the most secure.
Do both spouses need separate lawyers for a postnup?
It is not required by statute, but it is strongly recommended. Separate counsel on both sides was an important reason the Burkle court found no presumption of undue influence.
Can we just retitle property instead of signing an agreement?
Retitling alone is risky. California courts require an express written declaration of a change in character, and titles, account forms and conduct are generally not enough.
Can a postnuptial agreement waive spousal support?
This is an open question in California. There is no controlling authority holding a mid-marriage support waiver enforceable, so any support provision carries significant risk.
Can a postnup convert separate property into community property?
Yes. Family Code § 850 allows transmutation in either direction. Converting to community property can have income tax benefits at death, but it also gives the other spouse a half interest if the marriage ends.
Does Holmes Law represent both spouses?
No. Holmes Law represents one spouse, and the other spouse should have independent counsel.
Speak With a California Postnuptial Agreement Attorney
Holmes Law drafts and reviews California postnuptial agreements that satisfy the transmutation statutes and the fiduciary duties between spouses, coordinated with the couple’s estate plan. The practice is remote, so meetings happen by phone or video wherever you are in California. To discuss a postnuptial agreement, contact Holmes Law to schedule a consultation with Michael Holmes. Contacting Holmes Law does not create an attorney-client relationship, and this page is general information, not legal advice for your situation.