Does a Prenup Override a Will or Trust in California?

Short answer: Yes — a valid prenup or postnup can waive a spouse’s inheritance rights, including the “omitted spouse” share the law would otherwise give them (Prob. Code §§ 21610–21612), through a waiver under Prob. Code § 141. So a prenup can control what your spouse gets regardless of what your will or trust says or leaves out. But it only works if it was validly executed, and the prenup and the estate plan have to actually agree with each other.

Code sections verified against California Probate Code §§ 141 and 21610–21612 and the Family Code premarital agreement rules, 2026. This is general information, not legal advice for your situation.

What a prenup can waive

California doesn’t let you fully disinherit a spouse by accident. Two protections exist for a spouse who’s left out. First, the “omitted spouse” rule (Prob. Code §§ 21610–21612): if you made your will or trust before the marriage and never updated it, your surviving spouse can claim a share — roughly what they’d have gotten if you’d died with no plan at all. Second, a spouse’s community-property and other statutory rights on top of that.

A prenup or postnup can waive both. Under Prob. Code § 141, a spouse can give up, in writing, the right to a probate homestead, family allowance, the omitted-spouse share, the right to serve as executor, and more. When a couple signs “we each keep our own estates and waive any claim on the other’s,” that waiver is what makes it stick. So the document that really decides what your spouse can claim may not be your will — it may be the agreement you both signed before or during the marriage.

How the prenup and the estate plan work together

Think of it as two layers. The prenup sets the floor — what your spouse has waived and what they’ve kept. The will or trust then distributes your estate on top of that floor. A prenup can knock out a claim your spouse would otherwise have; it can’t force your will to leave them anything. So a prenup is powerful for subtracting rights, and your estate plan is where you add back whatever you actually want your spouse to receive.

Here’s a Ventura County example. A man remarries later in life. He and his second wife sign a prenup: each keeps their own property, and she waives any claim on his estate so his house can pass to his kids from his first marriage. He then writes a trust leaving the house to his children. The prenup and the trust point the same direction — his kids get the house, and his wife can’t invoke the omitted-spouse rule to grab a share, because she waived it under § 141. That’s the system working.

It only works if the prenup is valid

A prenup that a court throws out protects nobody. California’s premarital agreement rules (in the Family Code) set a real bar. To hold up, a prenup generally needs to be:

• In writing and signed voluntarily — no coercion, no “sign this or the wedding’s off” the night before.
• Backed by full, fair financial disclosure — you each have to know what the other has.
• Given real time to review — California imposes a waiting period between presenting the agreement and signing it.
• Ideally reviewed with independent counsel — each spouse with their own lawyer. If a party gives up counsel, the requirements to prove the agreement was voluntary get stricter.

Skip these and the whole waiver can collapse, which drops your spouse right back into their full statutory and omitted-spouse rights — the opposite of what the prenup was for. A postnup (signed after the wedding) can accomplish similar goals but faces its own scrutiny, because spouses owe each other a fiduciary duty once married.

The common failure: prenup and estate plan that contradict each other

This is where we see real trouble. The prenup and the estate plan get drafted years apart, by different people, and nobody checks that they agree. The classic conflict: a prenup says the wife waives all claims on the husband’s estate, but his trust — written later, or never updated — still leaves her a big chunk of it. Now which controls? You’ve built a lawsuit. Or the reverse: the prenup promises the spouse a certain share, but the will leaves them nothing, and the estate has to litigate the gap.

The fix is boring and effective: sync them. When you sign a prenup, your estate plan should be written or revised to match it, and every time you update one, check the other. In a blended family this is not optional — the mismatch is what turns a clear intention into a fight between your spouse and your kids. If your family is blended, the coordination matters even more; see blended family estate planning and how spousal inheritance rights in California work when there’s no waiver in place.

Common questions

Does a prenup override a will in California?

It can override the parts a spouse would otherwise be entitled to. A valid prenup can waive a spouse’s omitted-spouse share and other rights under Prob. Code § 141, so the spouse can’t claim against your estate even if your will is silent or predates the marriage. It can’t force your will to leave the spouse anything — for that, your will or trust has to actually name them.

Can a prenup disinherit my spouse entirely?

Effectively yes, if it’s valid and clearly waives the spouse’s inheritance rights. California normally protects a spouse from being left out through the omitted-spouse rules, but a § 141 waiver removes that protection. The catch is the waiver has to survive a validity challenge — voluntary, with full disclosure and fair process.

What makes a California prenup invalid?

Common killers are lack of full financial disclosure, signing under pressure or without enough time to review, and no independent counsel where the process wasn’t otherwise fair. California’s premarital agreement rules impose a waiting period and voluntariness requirements, and failing them can void the agreement — which restores the spouse’s full inheritance rights.

Do I still need a will or trust if I have a prenup?

Yes. A prenup mostly subtracts rights; it doesn’t distribute your estate. Without a will or trust, the rest of your intestacy rules still apply to everyone else, and any gap between the prenup and no plan invites confusion. The prenup and the estate plan are two halves of one arrangement.

What happens if my prenup and my trust say different things?

You’ve created a conflict that can end up in court. If the prenup waives the spouse’s claim but the trust leaves them assets — or vice versa — the two documents contradict, and your family may litigate which one controls. Keep them consistent and update both together.

The bottom line

A valid prenup or postnup can waive your spouse’s inheritance rights — including the omitted-spouse share — so it can absolutely control what your spouse gets, no matter what your will or trust says or leaves out. But it has to be validly executed to survive a challenge, and it has to match your estate plan. The failure we see most is a prenup and a trust that quietly contradict each other, drafted years apart with no one reconciling them. If you have a prenup, make sure your will or trust was written to agree with it — and when you change one, check the other. If you’re not sure the two are in sync, talk to Eric; reconciling them is a lot cheaper than the lawsuit a mismatch causes.

Sources: Cal. Prob. Code § 141 (waiver of spouse’s rights, including by premarital or marital agreement); Cal. Prob. Code §§ 21610–21612 (omitted spouse’s share); California premarital agreement requirements, Cal. Fam. Code §§ 1610–1617.