Valuing Unvested Equity in a Divorce

Part of Nauma's complete guide to Divorce & Financial Planning.

Once a court or a couple agrees that an unvested RSU or stock option grant is partly a marital asset, the next question is mechanical but consequential: exactly what percentage of it is marital, and what is that percentage worth in dollars? Getting the formula or the underlying dates wrong — even by a single month — can shift the outcome by tens or hundreds of thousands of dollars on a large grant.

This page covers the valuation methodology. For how the calculated marital share is actually divided between spouses, see Dividing RSUs and Stock Options in a Divorce.

The Coverture Fraction: The Basic Idea

A coverture fraction (also called a time rule) apportions an asset earned partly during the marriage and partly outside it by comparing the length of the "marital" period to the total period over which the asset was earned — measured against the grant's vesting schedule. The community or marital share equals that fraction multiplied by the total number of shares or options in the grant.

The two questions that determine the fraction are: what date does the numerator's clock start, and what date does the denominator's clock end? Two commonly used formulas answer the first question differently, producing materially different results from the same underlying grant.

The Hug Formula

Named for the 1984 California case In re Marriage of Hug, this formula runs the clock from the employee's date of hire to the date of separation (the numerator), divided by the period from date of hire to the grant's vesting date (the denominator). Because the clock starts at hire — which can include years of pre-grant employment — the Hug formula generally produces a larger marital share. It is typically applied when a grant is best understood as compensation for a continuum of service, such as a signing or hiring grant, or a hybrid grant rewarding both past and future contribution.

Formula: Marital share = (months from hire to separation) ÷ (months from hire to vesting) × shares in the grant

The Nelson Formula

Named for the 1986 California case In re Marriage of Nelson, this formula runs the clock from the date of grant to the date of separation (the numerator), divided by the period from date of grant to the vesting date (the denominator). Because the clock starts later — at grant rather than hire — the marital share is generally smaller. It is typically applied to grants understood as forward-looking incentives for future work and retention, such as an annual refresher RSU grant on a recurring cycle.

Formula: Marital share = (months from grant to separation) ÷ (months from grant to vesting) × shares in the grant

Note on terminology: both Hug and Nelson were decided on stock option grants, not RSUs. In those cases, the denominator's endpoint was the date the options became exercisable rather than a "vesting date." For RSUs — which vest and become owned simultaneously — "vesting date" is the correct term and the math is identical. If your grant consists of unexercised stock options, confirm with counsel whether exercisability or vesting controls the denominator in your jurisdiction.

A Worked Example

Consider an engineer hired in September 2018, who marries in January 2020, is granted 1,000 RSUs in September 2021 (vesting in September 2025), and separates from their spouse in January 2024.

Under Hug: months from hire (Sept. 2018) to separation (Jan. 2024) = 64 months. Months from hire to vesting (Sept. 2025) = 84 months. Marital share = 64 ÷ 84 = 76% → 762 shares.

Under Nelson: months from grant (Sept. 2021) to separation (Jan. 2024) = 28 months. Months from grant to vesting (Sept. 2025) = 48 months. Marital share = 28 ÷ 48 = 58% → 583 shares.

The same grant, the same dates — but which formula applies changes the marital share by nearly 180 shares. These figures are illustrative only and do not reflect any specific case outcome. This is why, as courts applying these formulas have noted, the choice between Hug and Nelson is not a math question at all — it is a characterization argument about what the specific grant was actually for, decided on the evidence of the grant's purpose, not on the formula either side prefers.

Why the Date of Separation Is the Single Most Important Input

In both formulas, the date of separation is the fixed cutoff that defines the end of the "marital" period, while the vesting date and grant or hire date are typically matters of record from the equity plan. This makes the date of separation — sometimes contested in its own right when spouses disagree about when they actually began living separately — a frequent point of dispute in equity-heavy cases, since even a one-month shift in that date can move a large grant's marital share by a meaningful dollar amount.

Putting a Dollar Value on the Marital Shares

Once the number of marital shares or options is established, they still need a dollar value, which depends on whether the company is public or private:

Public companies: Value is generally based on the stock's fair market value as of an agreed valuation date (often the separation date or a date close to trial), which is directly observable from the market.

Private companies: There is no market price, so valuation typically relies on the company's most recent 409A valuation, a recent priced funding round, or a forensic valuation expert's independent analysis — often using option-pricing models such as Black-Scholes for unexercised stock options. See Fair Market Value (FMV) for Private Company Stock for how 409A valuations work and why they are typically lower than headline funding-round valuations. Illiquidity and the risk of forfeiture before vesting are commonly factored in as discounts to the raw valuation number.

What This Page Does Not Cover

This page covers only the calculation of the marital share and its value — not how that value is actually paid out to the non-employee spouse (an if-and-when arrangement vs. a present-value buyout) or the tax treatment of the division. See Dividing RSUs and Stock Options in a Divorce for both.

California Note

Hug and Nelson are California cases, and while a number of other states have adopted similar time-rule reasoning for unvested equity, the specific formulas, terminology, and evidentiary standards for determining a grant's purpose vary by state — a couple relocating from California to an equitable-distribution state (or vice versa) during a long-running separation should confirm which jurisdiction's law actually governs their case rather than assuming Hug or Nelson automatically applies. Because most large California tech employers grant a mix of hiring grants and recurring annual refreshers, it is common for a single employee's total equity to require both formulas applied grant by grant, rather than one formula applied to the whole equity portfolio at once.

This article is for educational purposes only and does not constitute legal, tax, or financial advice. Coverture fraction methodology and which formula applies to a given grant are determined by the facts of each case and the law of the governing state. Always work with a family law attorney and, for significant equity positions, a qualified valuation expert before relying on any specific calculation.