The Founder's Prenuptial Agreement: Protecting Equity, RSUs, and Your Cap Table in California

Quick Answer: A prenuptial agreement is the most reliable way for a founder or tech professional to protect equity before marriage. Under California law, anything you build during the marriage is presumed to be community property, owned equally by both spouses, no matter whose name is on it. That includes the growth in value of a company you started, RSUs that vest while you are married, and stock options you exercise. A properly drafted prenup lets you decide in advance how your equity, your business interest, and your future grants will be treated, instead of leaving it to California's default rules and a forensic accountant years later. To be enforceable, the agreement has to be in writing, supported by full financial disclosure, and signed at least seven calendar days after the final version is presented. If you are getting married and you hold equity, contact The Geller Firm at (415) 840 0570 for a confidential consultation.

What Is a Prenuptial Agreement?

A prenuptial agreement, sometimes called a premarital agreement or simply a prenup, is a written contract that two people sign before they marry. It sets the financial terms of the marriage and, more importantly for most founders, the financial terms of a divorce while both spouses still have every reason to be fair to each other.

In California, prenuptial agreements are governed by the Uniform Premarital Agreement Act, found at Family Code section 1600 and following. The statute lets couples agree in advance on how property will be characterized and divided, how debts will be handled, and in many cases whether spousal support will be paid. The agreement becomes effective the moment the couple marries.

Without a prenup, your divorce is governed entirely by California's default community property system. Understanding that default is the only way to see what a prenup actually changes.

Why Founders and Tech Professionals Need a Prenup

California is a community property state. Under Family Code section 760, almost everything acquired during the marriage belongs equally to both spouses. Under Family Code section 770, property you owned before the marriage, along with gifts and inheritances, is your separate property. The line between the two is where founders get hurt, because the most valuable thing you own is rarely static. It grows, and the growth is where the fight happens.

Consider what the default rules do to common equity situations:

A company you started before the marriage. The business itself may be your separate property, but the growth in its value during the marriage may not be. When a separate property business increases in value because of your personal effort and labor during the marriage, California uses one of two formulas, Pereira or Van Camp, to decide how much of that growth the community gets to share. A founder who marries early and sells late can owe a spouse a meaningful share of an outcome built largely after the wedding.

RSUs and stock options that vest during the marriage. Equity granted and vested while you are married is generally community property. Equity that straddles the marriage, granted before but vesting after, or granted during but vesting past separation, gets divided by time based formulas that turn on exactly when the grant was made and what it was meant to reward.

A liquidity event during the marriage. An acquisition or an IPO that happens while you are married converts paper equity into real money, and the community property character of that money is decided by the timeline, not by whose name sits on the cap table.

A prenup lets you replace all of that uncertainty with a clear, agreed answer. You can define your equity as separate property, decide how future grants will be treated, and keep your company's ownership out of a contested divorce. For a deeper look at each of these issues, our blog covers how California divides RSUs and stock options, how founder equity is treated, and what happens to equity in an IPO or acquisition.

What California Law Requires for a Valid Prenuptial Agreement

A prenup is only worth the protection it provides if it holds up. California law sets specific requirements, and an agreement that misses them can be set aside at the exact moment you need it.

It must be in writing and signed. Under Family Code section 1611, a premarital agreement must be in writing and signed by both parties. Oral agreements are not enforceable, and the statute makes the agreement enforceable without consideration, meaning neither spouse has to give the other something of value for it to count.

Both parties must receive full financial disclosure. Under Family Code section 1615, an agreement can be challenged as unconscionable if, before signing, a party was not provided a "fair, reasonable, and full disclosure" of the other party's property and financial obligations, did not waive that disclosure in writing, and could not reasonably have known the other party's finances on their own. For a founder, this cuts in a direction many people do not expect. Full disclosure of your equity, your cap table position, and your real financial picture is not a threat to the agreement. It is what makes the agreement enforceable.

It must be signed voluntarily, and that includes a waiting period. Family Code section 1615 presumes an agreement was not signed voluntarily unless the court makes specific findings. For any agreement signed on or after January 1, 2020, one of those findings is a waiting period. The party must have had "not less than seven calendar days between the time that party was first presented with the final agreement and the time the agreement was signed, regardless of whether the party is represented by legal counsel." This is the seven day rule, and it applies even when both spouses have their own lawyers. In plain terms, you cannot hand your fiancé a prenup the night before the wedding and expect it to survive.

A spousal support waiver has its own rule. Under Family Code section 1612, any provision about spousal support, including a waiver of it, is not enforceable if the party giving up support was not represented by independent counsel when the agreement was signed. A support waiver can also be set aside if it is unconscionable at the time someone tries to enforce it. If your prenup touches spousal support, both spouses having their own lawyers is not optional.

What a Founder's Prenup Should Address

A generic prenup template is not built for equity. The agreement that actually protects a founder is specific about the things a founder owns. At a minimum, it should address:

Characterization of existing equity. State plainly that the equity you hold before the marriage, including founder shares, vested options, and any interest in your company, is and remains your separate property.

Treatment of future grants and vesting. Decide in advance how RSUs, options, and other equity granted or vesting during the marriage will be treated. This is the single most valuable thing a founder's prenup does, because it removes the time based apportionment fight before it can start.

Appreciation and the Pereira and Van Camp problem. Address what happens to the growth in value of your separate property business during the marriage. Without an agreement, that growth is decided by formula. With one, you decide.

Business control and the cap table. Confirm that your spouse will not acquire a management interest, a voting interest, or a claim on the company's ownership through the marriage, which protects your cofounders and investors as much as it protects you.

Spousal support. Decide whether support will be paid, limited, or waived, with both spouses independently represented so the provision holds.

Separate and community debts. Allocate responsibility for debts, including any debt tied to the business.

Each of these decisions interacts with California's default rules, including how separate and community property are characterized and how the date of separation cuts off the community estate. Getting them right is part legal drafting and part financial modeling, which is where the real value lives.

Common Mistakes That Make a Prenup Unenforceable

Founders are detail oriented, but a prenup fails on procedure as often as it fails on substance. The recurring mistakes are avoidable:

Signing too close to the wedding. Violating the seven day rule is the fastest way to lose the agreement. Start months ahead, not weeks.

Hiding the ball on disclosure. Understating your equity or leaving an asset off the disclosure invites a challenge. Full, documented disclosure protects the agreement.

Skipping independent counsel. One lawyer cannot represent both sides. If your spouse does not have their own attorney, a spousal support waiver is not enforceable and the whole agreement is more vulnerable.

Using a generic template. A form prenup that never mentions RSUs, vesting schedules, or business appreciation leaves your most valuable assets governed by the default rules anyway.

Pressure and timing. An agreement presented under obvious pressure, or signed in circumstances that look like duress, can be attacked as involuntary regardless of what it says.

Why the Financial Modeling Matters as Much as the Legal Drafting

Most prenups are drafted by lawyers who can recite the statute but cannot model the numbers. That gap is exactly where founders lose value. The clauses that matter most in a founder's prenup, characterizing future grants, handling business appreciation, and deciding how a liquidity event is treated, are financial questions wearing legal clothing. You cannot draft them well unless you can run the math on what each version actually does to your equity across different outcomes.

That is the lens we bring. With a JD, an MBA, and the ability to read a cap table and a vesting schedule, we draft the legal terms and model the financial result at the same time, so you can see what each choice means before you sign rather than after a forensic accountant explains it in a deposition. You should be able to model your own numbers, and a prenup is the one document where doing that work upfront pays off the most.

Frequently Asked Questions

Does a prenup mean I expect the marriage to fail?

No. A prenup is risk planning, the same discipline you apply to your company. Founders insure against outcomes they do not expect and do not want. A prenup is that same insurance applied to your personal balance sheet.

Can a prenup protect equity I have not been granted yet?

Yes. A well drafted agreement can set how future RSUs, options, and grants will be characterized, even ones that do not exist on the signing date. This is one of the strongest reasons for a founder to sign one.

My fiancé and I do not have many assets yet. Is it too early?

For founders, early is the best time. If your company is pre revenue or pre funding today, its value is low and the conversation is easy. The agreement you sign now governs the upside you have not built yet.

What happens if we skip the prenup and divorce later?

California's default community property rules apply. Your equity, business growth, and vested grants are characterized and divided under those rules, often with a forensic accountant tracing and valuing everything, which is slower, costlier, and far less predictable than an agreement.

Can we change the agreement after we are married?

Yes, but it is harder. After marriage, spouses owe each other a fiduciary duty, and changing the character of property has to satisfy California's transmutation requirements. A postnuptial agreement is possible, and we cover it in a companion post, but the cleanest protection is signing before the wedding.

Speak With a California Family Law Attorney

If you hold equity and you are getting married, a prenuptial agreement is the most direct way to protect what you have built and what you are still building. The agreement has to be drafted with care, supported by full disclosure, and signed on the right timeline, and the equity provisions have to be modeled, not just written. The Geller Firm represents founders, executives, and high net worth professionals across California in premarital agreements involving equity, business interests, and complex financial planning. We offer confidential virtual and in person consultations from our Walnut Creek office.

Call (415) 840 0570 or contact us online to schedule your consultation.