California Taxes on RSUs and Stock Options: A Tech Employee's Guide

If you work in tech in California, you're already in the highest-taxed environment in the country for equity compensation. California's top marginal income tax rate is 13.3%. Unlike the federal government, California offers zero preferential treatment for long-term capital gains — it taxes everything at ordinary income rates. And its nonresident sourcing rules mean California can reach into your tax return years after you leave the state.

This guide covers what every tech employee in California needs to understand about how RSUs, ISOs, NSOs, and deferred compensation are taxed — and the nonresident rules that matter if you ever consider moving.

California's tax structure for high earners

Most tech employees earning $200K+ are in the 9.3%–12.3% CA bracket range. Add 1.3% SDI and federal rates (22%–37% plus net investment income tax), and the combined marginal rate on RSU vests for a Bay Area senior engineer can approach 55%.

RSUs: taxed at vest, at California's full rate

When your RSUs vest, the fair market value at vest is ordinary income — to both the IRS and the California FTB. If you're a California resident, 100% of that income is California-sourced. Your employer withholds federal income tax (typically at the 22% supplemental rate, which underwithholds for most tech employees), Social Security, Medicare, and CA state income tax.

The important nuances:

• The 22% withholding trap applies at the state level too. California employers withhold at a flat supplemental rate that may be lower than your actual CA marginal rate. Check your paystub and plan for a tax-time true-up.
• Holding after vest creates a separate capital gain (or loss). Your cost basis in the shares equals the FMV at vest. Appreciation after that date is a capital gain when you sell — taxed at federal LTCG or short-term rates, but still at full CA ordinary income rates regardless of holding period.
• Selling immediately (sell-to-cover) is often the cleanest choice for most RSU holders, since the only incremental tax from holding is hoping for LTCG treatment at the federal level (which saves 15–20% federal but zero CA).

ISOs: no California preferential treatment

Incentive Stock Options are taxed by the federal government as a potential AMT item at exercise (the spread between FMV and strike price is an ISO preference item), with favorable LTCG treatment at sale if you meet the qualifying disposition holding periods (2 years from grant, 1 year from exercise).

California does not conform:³

• At ISO exercise, California treats the spread as regular income — creating a California-only tax event even though you owe no federal regular tax.
• California has its own AMT at a 7% rate. ISO exercise creates a California AMT preference item. In practice, you may owe California AMT on large ISO exercises even if your federal AMT calculation results in no federal AMT owed.
• At sale, even if you qualify for federal LTCG rates, California taxes the full gain at ordinary income rates. There is no California capital gains preference.

NSOs: exercise triggers ordinary income in California

Non-qualified stock options are taxed at exercise: the spread between FMV and strike is ordinary income to both the IRS and California FTB, subject to withholding. The tax treatment is simpler and worse than ISOs — no AMT complexity, but also no potential preferential rate at sale (the post-exercise appreciation is capital gain, but again, California taxes that at ordinary income rates).

The exercise decision for NSOs in California is entirely driven by your view on the stock relative to your current vs. expected future marginal rate. If you expect to leave California before a liquidity event, timing becomes important — see the nonresident section below.

The California long arm: nonresident sourcing rules

This is where California tax planning for tech employees gets genuinely complex — and where most people are surprised.

If you worked in California during the grant period of your equity comp, California claims a portion of the income even after you move to a no-income-tax state. The allocation method, per FTB Publication 1004:⁴

A concrete example: You receive a 4-year RSU grant while working at a Bay Area tech company. After 2 years (spending 100% of that time in California), you move to Austin, Texas. At the 3-year vest of those shares — even though you're a Texas resident — California claims approximately 2/3 of the income from those shares (24 CA months ÷ 36 total months). You'll file a California nonresident return (Form 540NR) and pay CA tax on that 2/3 allocation.

This nonresident sourcing rule has been upheld by the California Office of Tax Appeals and applies even if you never set foot in California again during the year of vesting.⁵ The longer your grant-to-vest period and the more time you spent in California before moving, the larger California's share.

Deferred compensation: California's source rule is aggressive

Non-qualified deferred compensation (NQDC) earned during California employment is treated as California-sourced income when paid — even if you've moved to another state by the time you receive it.⁴

Under California Revenue and Taxation Code §17952 and the FTB's interpretation, the sourcing for NQDC is based on where the services were performed that gave rise to the compensation. This is called the "source rule" and it's more aggressive than most states' approach.

This doesn't mean NQDC deferrals are a bad idea for California residents — the calculation depends on your CA rate now vs. your expected rate and state of residency at distribution. But it does mean you should factor the CA source rule into the decision, not assume a move to a no-tax state cleans the slate.

The interstate move question

California's equity sourcing rules make this calculation more nuanced than it appears. The key variables:

• How much of your unvested equity was granted while in CA? California's share of future vests is locked in at grant. Moving before vesting reduces California's claim on future grants — but doesn't change the allocation on existing grants.
• How much unexercised ISO/NSO do you have? Moving before exercise can reduce California's share on the grant-to-exercise period, but only for the portion of the period spent outside CA.
• When is the likely liquidity event? For QSBS and large gains, the post-exercise appreciation is a separate capital gain — California taxes that gain at ordinary income rates only if you're a CA resident when you sell. Moving before selling changes the calculus for that component.

The honest answer is that moving from California for tax purposes can save meaningful dollars for tech employees with large unvested or unexercised equity — but the savings are often smaller than people expect because of the nonresident sourcing rules. Getting the numbers right requires modeling your specific grant schedule, vest dates, and expected liquidity timeline.

What a fee-only advisor can help you model

• The exact CA tax owed on each tranche of RSU vests or option exercises, including withholding gap
• Whether an ISO exercise strategy is worth it given your CA rate vs. federal AMT exposure
• The true after-tax benefit of moving before a liquidity event, given your specific grant schedule
• Whether NQDC deferrals make sense given CA's source rule and your expected future state of residency
• How to document CA workdays for the allocation if you've already moved or work remotely