How RSUs Are Taxed in California for Married Founders in 2026

How RSUs Are Taxed in California in 2026

RSUs are taxed twice in California: once as ordinary W-2 income on the day they vest, and again on any appreciation when you sell the shares. For high-earning founders, the combined marginal rate at vesting can push past 52% once you stack federal, state, Medicare, and disability components.

Here's the mechanic. When your restricted stock units (grants of company shares that convert to actual stock once time or performance conditions are met) vest, the fair market value of those shares on the vest date becomes ordinary wage income. It lands on your W-2 exactly like salary or a bonus. If 1,000 shares vest at $150 each, $150,000 gets added to your taxable wages that year, whether or not you sell a single share.

The second layer comes at sale. Any gain above the vest-date value is a capital gain. Federally, holding for more than a year gets you a preferential long-term capital gains rate. California is different. The state taxes all capital gains as ordinary income, with no preferential rate, so appreciation on shares you hold is taxed at your full California marginal rate up to 13.3%.

For married founders, this creates two planning questions at once: how to cover the tax owed at each vest, and how to treat concentrated stock as a shared household asset. Both are easier to address with aligned, professionally guided planning rather than a scramble every April.

California's RSU Tax Rate Stack for 2026

The reason RSU income shrinks so fast is that several taxes apply to the same dollar at the same time. Here's what stacks on a vest for a high earner in 2026:

• Federal ordinary income tax up to 37% on the vest-day value.
• Additional Medicare Tax of 0.9% on wages above $200,000 (single) or $250,000 (married filing jointly), under IRC Section 3101(b)(2).
• California income tax up to 13.3%, which is the 12.3% top marginal bracket plus a 1% Mental Health Services Tax on taxable income over $1 million.
• California SDI (State Disability Insurance), which became uncapped on January 1, 2024. It now applies to every dollar of wages with no ceiling, so high-earner RSU vests pay it on the full amount per the EDD's annual contribution rate.
• Net Investment Income Tax (NIIT) of 3.8% federally, which applies to post-vest capital gains for high-AGI households under IRC Section 1411.

California's brackets are progressive and inflation-indexed each year. The 2026 figures below are indexed estimates. Verify exact thresholds at ftb.ca.gov before you plan a specific vest.

Most tech workers earning between $70,000 and $360,000 of total income sit in the 9.3% California bracket. Stack the federal 37%, the 0.9% Medicare surtax, and uncapped SDI on top, and the all-in marginal rate for someone in the federal top bracket lands near or above 51%. The supplemental withholding rates set by the EDD and the IRS don't come close to matching that, which is where the problem starts.

Why Your Employer Withholds Too Little on RSU Vests

Your employer withholds a flat 22% federal on RSU vests, but if your income puts you in the 37% bracket, you're short by 15 points on every dollar. That gap is not a payroll error. It's baked into how supplemental wage withholding works.

Under the supplemental wage rules in IRS Publication 15, employers withhold a flat 22% on cumulative supplemental wages up to $1 million per employee per calendar year, then 37% above that threshold. That flat 22% is a withholding convention, not your tax rate. It exists so payroll can apply one number across thousands of employees without knowing each person's full income picture. It works fine for someone earning $90,000. It fails badly for a household clearing $700,000.

California has the same problem. The state's supplemental rate for stock and bonuses is 10.23%, set by the EDD in Publication DE 44. But your actual California marginal rate may be 11.3%, 12.3%, or 13.3%. California does not gross up to fix the difference either.

Put the two together on a $300,000 vest and the combined federal and state shortfall can exceed $51,000. That arrives as a balance due in April, usually to someone who assumed the taxes were already handled at vest. The fix has to happen before December 31 of the vest year, either through extra payroll withholding or estimated payments. April is too late to change what was withheld.

How California Community Property Rules Affect Married Founders' RSUs

In California, RSUs earned during the marriage are generally community property, owned 50/50 by both spouses regardless of whose name is on the grant. Under California Family Code §760, community property is all property acquired by either spouse during the marriage while domiciled in California, other than gifts, bequests, or inheritance.

The line that gets contested is between community and separate property. Separate property includes assets owned before the marriage, plus gifts and inheritances received during it. RSUs granted before marriage but vesting after, or grants tied partly to pre-marriage service, raise tracing questions (documenting the source and timing of each tranche to establish its character). Those questions matter both for tax filing and for how a couple understands their shared balance sheet.

Filing status changes how visible this is. When you file married filing jointly, the joint return aggregates everything, so the 50/50 split is invisible. When you file married filing separately, the split drives the return through Form 8958, which allocates income between spouses in community property states, with California Form 540 following the federal allocation.

For couples, this is a chance to treat equity as a joint asset from the start rather than an individual line item. As Michael C. Cotugno, Esq., Managing Partner at Neptune Legal, puts it, "Fairness in a conscious partnership transcends mere numbers." Aligning early on how equity is characterized and how taxes on it are shared builds clarity that holds up whether you file jointly or separately.

California Sourcing Rules When Founders Move Out of State

California taxes RSU vesting income based on where you worked during the vesting period, not where you live when the shares vest. If you earned a grant while working in California and then moved to Texas before it vested, California still gets a share of every vesting tranche.

The methodology is workday allocation. For each tranche, the vesting period generally runs from the grant date to that tranche's vest date. California claims the proportion of vesting-period workdays you spent in California. So a four-year grant vesting 25% per year sources each tranche differently:

• Tranche 1 (vests year 1): vesting period is 1 year. California-source portion is based on the share of that year's workdays in California.
• Tranche 2 (vests year 2): vesting period is 2 years.
• Tranche 3 (vests year 3): vesting period is 3 years.
• Tranche 4 (vests year 4): vesting period is 4 years.

If you worked in California for the first two years and then moved, the earlier tranches carry a much higher California-source percentage than the later ones. Moving out of state does not erase California's claim on the workdays you already spent there. The FTB applies similar logic to performance-based units (PSUs), where vesting depends on hitting milestones.

Multi-state allocation gets complicated fast, especially with overlapping grants and mid-year moves. Departing founders generally benefit from working with a CPA who handles California sourcing, so the allocation is documented correctly and you don't overpay or trigger an audit.

How Married Founders Should Plan for RSU Taxes in 2026

The planning framework is simple to state and worth doing every year: estimate the withholding gap, then close it before December 31. You can bump withholding through Form W-4 line 4(c) for extra per-paycheck withholding, or make a Q4 estimated payment to the IRS and the FTB. Waiting until you file means the shortfall is already locked in, plus potential underpayment penalties.

Beyond covering the bill, married founders should look at sell-to-cover analysis (selling a portion of vested shares to fund the tax owed) and how much concentrated employer stock to hold as a couple. A large unhedged position in one company's stock ties your household's net worth to a single employer, and California's rate stack makes that concentration expensive to unwind later since there's no preferential capital gains rate to soften the sale.

Equity compensation rarely sits in isolation. It connects to your estate plan, your combined tax picture, and the agreements you build as partners. "For entrepreneurs and dedicated professionals, their work is often far more than a job; it is a profound expression of their purpose and identity," says Michael C. Cotugno, Esq., Managing Partner at Neptune Legal. Planning around that work as a couple means treating equity as shared, not separate.

This is where Neptune helps. Neptune pairs couples with experienced attorneys, CFPs, and CPAs, and shepherds the full process from the first conversation through drafting and filing. If you and your partner want structured guidance on RSU taxes, community property, and how equity fits your long-term plan, see how it works. Independent counsel for each partner is highly recommended for an enforceable prenup, and the same principle of clear, separate professional input applies across tax and estate planning. Couples who plan together, grow together.