How RSU Vests Are Taxed in California (2026)
California has the highest top marginal income rate in the country and stacks supplemental withholding on top. If you work at a FAANG, late-stage startup, or any public-tech employer, the gap between what gets withheld and what you actually owe is wider here than anywhere else.
Use the RSU Calculator to model your exact vest with California state withholding, FICA, and sell-to-cover analysis.
Open RSU Calculator →When RSUs vest in California, the full FMV of the shares becomes ordinary W-2 wages on the day they vest — and your employer is required to withhold federal supplemental tax (22% under $1M, 37% above), FICA (7.65% up to the 2026 SS wage base of $184,500, then 1.45% Medicare), California supplemental at 10.23%, plus an additional 0.9% Medicare surtax once your year-to-date earnings cross $200,000 single / $250,000 MFJ.
The 22% federal flat rate is the single biggest source of underwithholding for California tech workers. If your salary alone puts you in the 32% or 35% federal bracket, every vest leaves you 10–15 percentage points short federally — and CA does not gross-up to fix it. The 10.23% state supplemental is also below the 11.3% / 12.3% / 13.3% you may actually owe at the top of the bracket. Plan for an April balance due unless you proactively bump withholding via Form W-4 line 4(c) or make a Q4 estimated payment.
How California withholds on RSU vests
California treats RSU vest income exactly like a bonus — it is "supplemental wages" under FTB Pub 1001. Employers default to the 10.23% state flat rate, even though most public-company employees are in the 9.3–13.3% range by the time vest income stacks on top of base salary.
On a $300,000 vest in San Francisco for an engineer earning $250,000 base, total withholding typically lands around 39–41% (22% fed + 7.65% FICA + 10.23% CA + 1.45% Medicare additional tier). Actual liability on the marginal dollar is closer to 47–50% federal+state+FICA combined. The shortfall on a single $300K vest can exceed $25,000.
- •10.23% CA state supplemental on stock & bonus wages
- •22% federal flat rate (37% above $1M YTD supplemental)
- •6.2% Social Security up to $184,500 (2026), 1.45% Medicare uncapped, +0.9% over $200K single / $250K MFJ
- •1% additional Mental Health Services Tax above $1M of CA taxable income
- •No state-level reciprocity; remote workers vesting while CA-resident pay full CA tax
RSU concentrations by California metro
Where you live inside California affects almost nothing tax-wise (CA is uniform statewide), but local salary norms shift what your effective vest looks like. These ranges reflect typical L4–L6 / IC4–IC6 public-company total comp.
FAANG, OpenAI, Anthropic, Stripe — RSU often 50–65% of TC at senior levels.
NVIDIA, Apple, Google, Meta — refresher grants stack heavily on hire-on grants by year 3.
Snap, Disney/streaming, Riot, Activision-Blizzard, Hulu — RSU heavier in entertainment-tech.
Qualcomm RSU very common; biotech (Illumina, Dexcom) RSU + ESPP combined.
Sample California RSU take-home
Federal flat-22% withholding + CA 10.23% + FICA. Numbers exclude pre-tax 401(k) reductions and sale of shares.
| Scenario | Withheld | Actual Owed | Shortfall |
|---|---|---|---|
| $100K vest, $200K base | ~$39,000 | ~$45,500 | ~$6,500 |
| $300K vest, $250K base | ~$117,000 | ~$144,000 | ~$27,000 |
| $500K vest, $300K base | ~$195,000 | ~$245,000 | ~$50,000 |
Estimates assume single filer, standard deduction, no other supplemental wages. Real numbers vary by deductions, filing status, and 401(k) contributions. Run your own scenario →
Tactics that actually move the needle in California
- 1File a fresh W-4 with extra federal withholding on line 4(c) the first paycheck after a large vest — this is the cleanest way to avoid an April surprise without making estimated payments.
- 2Sell-to-cover only covers the 22% statutory rate. If you are in the 32%+ federal bracket, plan to sell additional shares yourself or set aside cash equal to 12–15% of the vest FMV.
- 3Max your 401(k) ($24,500 in 2026) and HSA ($4,400 single / $8,750 family) — both reduce CA taxable income dollar-for-dollar.
- 4If you cross $1M of CA taxable income, the 1% Mental Health surcharge kicks in. A donor-advised fund contribution late in the year is the most liquid way to trim the top.
- 5Mega-backdoor Roth: if your employer plan allows after-tax contributions + in-plan conversions, you can shelter another $47,500 (2026) of RSU cash flow into Roth.
- 6For shares you keep, the cost basis = FMV at vest. Track this — every brokerage in 2014–2018 reported $0 basis on 1099-B and people double-paid. Adjust on Form 8949.
- 7If you plan to leave California, vest before residency change is what locks CA in. Pre-departure tax planning needs 6–12 months of runway.
Frequently asked questions
No — at vest, RSU value is just W-2 wages. The only quirk is supplemental withholding (10.23% CA, 22% federal flat) which is usually below your true marginal rate. Long-term capital gains on shares you keep and sell after 12+ months are also taxed as ordinary income in California — there is no preferential CA rate for LTCG, unlike federal.
CA taxes RSU vest income based on where you worked during the vesting period (the grant-to-vest window). If shares were granted while you were a CA resident and 50% of the vest period happened in CA, CA will pull 50% of the vest income via FTB sourcing rules. This is one of the most-audited areas for departing tech workers.
Once your total CA taxable income (W-2 + vests + everything) exceeds $1,000,000, every dollar above that gets an additional 1% on top of the 12.3% top bracket — so 13.3% on the marginal dollar. Most tech workers hit this only in vest-heavy years (refresher cliff vests, IPO unlock).
Yes — and California specifically does NOT conform to federal ISO/AMT rules in some respects. Use the ISO/AMT calculator for federal; CA AMT applies separately at 7%, with its own exemption ($117,468 single / $156,624 MFJ for 2024 — adjusted annually).
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