Prenups for Startup Founders With Vesting Schedules

Why Founders With Vesting Equity Need a Prenup Conversation

A prenup lets founders and their partners decide together how vesting equity is classified, replacing state default rules with a shared agreement you both shape. Without one, the state decides for you, and the default formulas weren't built for the way startup equity actually works.

Vesting schedules are what make this conversation especially important. Most startup equity follows a time-based schedule: typically a one-year cliff (nothing vests until you hit the 12-month mark) followed by monthly or quarterly vesting over the next three years. If you received a grant before the wedding that keeps vesting after it, you've got equity straddling two legal categories. The portion earned before marriage may be separate property. The portion earned during marriage is, in most states, marital or community property. The line between those two categories isn't always obvious, and that's exactly where a prenup provides clarity.

As Michael C. Cotugno, Esq., Managing Partner of Neptune Legal, puts it: "For entrepreneurs and dedicated professionals, their work is often far more than a job; it is a profound expression of their purpose and identity."

That's why this conversation is best had early, while the numbers are still small and the tone is collaborative. A prenup drafted when your shares are worth $0.50 each feels like planning. The same conversation after a $50 million Series B feels like something else entirely. Framing equity decisions as part of building your life together, rather than as a defensive measure, sets the foundation for how you'll handle financial decisions throughout your marriage.

How Vesting Schedules Affect Whether Equity Is Marital Property

Equity granted during marriage is generally marital or community property by default. But grants that begin before the wedding and vest during the marriage create split-portion questions, and the answers depend almost entirely on timing.

Here's where it gets specific. Consider a standard four-year vesting schedule with a one-year cliff. If you received the grant two years before your wedding, 50% of the total grant may have vested before marriage (separate property), while the remaining 50% vests during the marriage (potentially marital property). The actual calculation depends on your state and sometimes on the purpose behind the grant, but timing is the core variable.

Time-Based vs. Performance-Based Vesting

Time-based vesting is the most common structure: you earn equity simply by staying employed. Classification here tracks the calendar. Performance-based triggers, on the other hand, tie vesting to hitting specific milestones like revenue targets or product launches. These triggers can make the marital vs. separate analysis harder, because the "when" of vesting isn't predictable at the time the grant is made.

Community Property vs. Equitable Distribution States

The state you live in shapes the default rules:

In community property states, equity earned during marriage belongs equally to both spouses by default. In equitable distribution states, a court has discretion over what's "fair," which introduces more uncertainty. Either way, a prenup replaces the default with a rule you and your partner choose together.

For more on how equity is treated across different state frameworks, see our guide on prenups for tech workers.

Stock Options, RSUs, and Pre-IPO Founder Stock Explained

Founders typically hold one or more of three equity types, and each one is treated differently in a prenup because of how ownership, taxation, and liquidity work.

Incentive Stock Options (ISOs) give you the right to buy company shares at a set price (the strike price). If you hold the shares for at least one year after exercise and two years after the grant date, any gain is taxed at the lower long-term capital gains rate. ISOs have a $100,000 annual vesting limit (2024); anything above that threshold is treated as a non-qualified stock option.

Non-Qualified Stock Options (NSOs) work similarly, but the spread between your strike price and the fair market value at exercise is taxed as ordinary income. NSOs don't carry the same holding-period tax advantages as ISOs.

[RSUs (Restricted Stock Units)](https://meetneptune.com/blog/rsu-iso-nso-prenup-equity-compensation) are promises of actual shares delivered once vesting conditions are met, usually continued employment for a set period. Unlike options, you don't pay a strike price. When RSUs vest, their full value is taxed as ordinary income in that year.

Founder or Pre-IPO Stock is equity in a private company that hasn't had a liquidity event. It's often the most valuable asset a founder holds, and also the hardest to value. Pre-money vs. post-money distinctions matter here: a founder who owns 20% of a company valued at $5 million pre-money holds equity with a notional value of $1 million, but that same 20% might dilute to 15% after a new funding round, even as the post-money valuation rises.

Why Documenting Value at Signing Matters

A prenup should include the current fair market value of all equity at the time of signing. For private companies, this typically means referencing the most recent 409A valuation, which the IRS requires companies to perform for stock compensation purposes. If your company's 409A valuation sets the fair market value at $2 per share when you sign the prenup, and shares are worth $80 per share at an IPO three years later, the prenup can specify how that $78 per share appreciation is treated. Without that documented baseline, any future dispute starts with a fight over what the equity was worth in the first place.

For California-specific founders, our article on startup equity prenups covers the Family Code provisions in detail.

How Courts Divide Unvested Equity Without a Prenup

Without an agreement, courts apply default time-rule and coverture-fraction formulas that may split appreciation in ways neither partner would choose if asked. The math isn't inherently unfair, but it's impersonal, and the litigation required to reach a number is expensive.

The Coverture Fraction

The coverture fraction is borrowed from pension-division case law and applied to unvested equity in many states, including Florida. The formula allocates equity between the premarital and marital periods based on how much of the vesting period fell within the marriage.

Here's a concrete example: a founder receives a stock option grant with a four-year vesting schedule. The grant starts two years before the wedding. The couple separates two years after the wedding, when all options have vested. The coverture fraction is 2 (years of vesting during marriage) divided by 4 (total vesting years) = 50%. Under this approach, roughly half those options would be characterized as marital property.

California's Default Formulas

California courts use two specific time-rule formulas for unvested stock options and RSUs:

• The Hug formula applies when a grant was primarily intended to compensate for past services. It tends to allocate a larger share to the community (marital) portion.
• The Nelson formula applies when a grant was meant to incentivize future work. It tends to favor the employee spouse.

Neither formula is mandatory, and courts retain broad discretion to modify the approach based on the facts. Beyond stock-specific formulas, California also uses Pereira and Van Camp apportionment methods for business interests generally, adding another layer of default math a prenup can replace.

The Cost of Ambiguity

When equity classification is contested, both sides typically need forensic accountants, detailed grant-document reviews, and financial analysis. That process can cost $20,000 to $100,000+ per side in legal and expert fees, before anyone reaches a courtroom. A prenup that addresses vesting equity specifically can reduce or eliminate that expense.

Our option vesting guide walks through the mechanics in more detail.

How to Structure Founder Equity in a Prenup: A Middle-Ground Framework

A prenup can designate premarital shares as separate while sharing some upside with your partner, so couples don't have to choose all or nothing. The best structures reflect what both partners actually value.

Here are some of the most common approaches:

These structures aren't mutually exclusive. A founder might keep pre-marriage equity separate, share liquidity proceeds above a threshold, and treat post-marriage RSU grants as community property, all in the same agreement.

New grants and refresh awards issued after the wedding naturally raise different questions than the founder stock you brought into the marriage. Many couples find it fair to treat post-marriage compensation differently from pre-marriage ownership. The prenup is where you make that distinction explicit.

For a deeper look at pre-liquidity considerations, including how IPOs and tender offers interact with prenup provisions, see our article on vesting equity for couples.

Working With Attorneys, CFPs, and CPAs to Draft a Founder Prenup

An enforceable founder prenup requires grant-specific language that standard templates miss, plus full financial disclosure, independent counsel for each partner, and adequate review time. This isn't a document you want to draft from a $299 form.

Why Templates Fall Short

A generic clause stating "all stock options remain separate property" is unlikely to hold up under scrutiny. California courts, for example, look closely at vesting schedules, the purpose of compensation, community contributions during marriage, and income characterization. A template that doesn't address these specifics leaves gaps that a court may fill with its own default rules.

What Neptune's Process Looks Like

Neptune manages the full end-to-end process for couples working through a prenup. You're paired with experienced attorneys who understand equity compensation, plus CFPs and CPAs who can help you think through the tax implications of different structures. For example, if you're deciding whether to share RSU income or keep it separate, a CPA can model the tax impact of each approach across different income scenarios.

The process is designed so both partners feel informed and involved. Neptune's platform provides education on how equity works in a prenup before you sit down with your attorney, so the legal conversations are more productive from the start.

Enforceability Requirements

Regardless of which state you're in, certain baseline requirements make a prenup enforceable:

• Full financial disclosure: both partners must provide a complete picture of their assets, debts, and income, including all equity grants and their current values.
• Independent legal counsel: each partner should have their own attorney. Independent counsel for each partner is highly recommended for an enforceable prenup.
• Adequate review time: in California, both partners must have at least 7 calendar days to review the final agreement before signing, per California Family Code section 1615.
• No coercion or duress: the agreement must be signed voluntarily by both parties.

For founders specifically, "full financial disclosure" means listing every equity grant, its vesting schedule, its current fair market value (using a 409A valuation for private companies), and any upcoming funding events or liquidity milestones. Skipping this step is one of the most common reasons founder prenups get challenged later.