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California RSU Tax Calculator

RSUs vest as ordinary income at the vesting price. California treats RSU vests identically to W-2 wages — your full bracket math applies. Most employers withhold at the federal supplemental rate (22%), which under-withholds for high earners and creates an April surprise.

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By Bennett · Founder & editor

Reviewed

This calculator estimates the withholding on your vest event AND flags whether you're likely to owe additional tax at year-end based on your true marginal rate.

Estimate your RSU vest taxes

Enter the dollar value of shares vesting (price × number of shares) and your regular salary.

$

Number of shares vesting × current share price. Becomes ordinary W-2 income on the vest date.

$

Used to estimate your true marginal rate for the year-end shortfall calculation.

Estimated take-home from vest

$32,228

from $50,000 vest — withheld at 35.5%

Default sell-to-cover withholding

  • Federal (22% supplemental)$11,000.00
  • California (10.23%)$5,115.00
  • Social Security$62.00
  • Medicare + Additional$995.00
  • CA SDI$600.00
  • Total withheld$17,772.00

How RSUs are taxed in California

Restricted Stock Units (RSUs) are taxed at two distinct moments:

  1. At vesting — the fair-market value of the vesting shares becomes ordinary W-2 income. Both federal and California taxes apply at your normal income tax brackets. This is what the calculator above estimates.
  2. At sale — any gain or loss between the vesting price (your cost basis) and the eventual sale price is treated as a capital gain or loss. Long-term capital gains (held over 1 year) get preferential federal rates (0/15/20%); California taxes them as ordinary income.

The vesting event is where most RSU surprises happen because withholding is automatic and often inadequate.

The 22% sell-to-cover problem

When your shares vest, your employer typically withholds enough shares to cover taxes — this is called "sell-to-cover." The default withholding rate is the federal supplemental rate of 22% (jumps to 37% on portions above $1M/year).

If your true marginal federal rate is 24%, 32%, or 35% — which it likely is if you're earning enough to receive RSUs — the 22% default leaves you owing additional federal tax at year-end. California's 10.23% supplemental withholding tracks closer to its 9.3-11.3% brackets but can also under-withhold at the highest tiers.

Common scenarios

Tech IC at $180k base, $50k annual RSU vesting

Default withholding: ~41% combined (22% federal + 10.23% CA + 7.65% FICA + 1.2% SDI). Net cash to you from the vest is roughly 60% of gross value. Year-end shortfall risk: low — usually within $1-2k of true tax owed.

Senior engineer at $250k base, $200k annual RSU vesting

Now in 32% federal and 9.3% California brackets. The 22% federal default under-withholds by ~10 percentage points. On $200k of RSU value, that's a $20,000+ year-end shortfall. Mandatory to either increase W-4 withholding or make estimated tax payments.

Director-level $400k+ with quarterly $300k vests

You're in 35-37% federal brackets and 10.3-11.3% California. The 22% federal supplemental catastrophically under-withholds. Plan for tens of thousands of additional federal tax owed. Working with a CPA on quarterly estimated payments becomes essential, not optional.

The cost-basis trap on later sale

When you eventually sell vested shares, your cost basis is the price they vested at, not your purchase cost. As of 2014, brokerages report only the price you paid (which is usually $0 for RSUs).

Common mistake: treating the entire sale value as gain. If your $50k of vested shares is sold a year later for $55k, your taxable gain is $5k (the appreciation), NOT $55k. The underlying $50k was already taxed at vest. You need to manually adjust your cost basis on your tax return — one of the most common sources of overpayment for RSU recipients.

Strategies for managing RSU tax exposure

  1. Increase W-4 federal withholding right after a vest event to cover the gap between 22% supplemental and your true marginal rate.
  2. Make a Q4 estimated tax payment if you can't adjust W-4 mid-year. This avoids underpayment penalties.
  3. Sell-to-cover plus a buffer — some companies allow you to elect higher withholding at vest. Check your equity portal.
  4. Hold to long-term capital gains if you believe in the company. Federal LTCG rates (0/15/20%) are lower than ordinary rates. California still taxes the gain at ordinary rates, but the federal savings are meaningful for high earners.
  5. Tax-loss harvest other holdings in years with large vest events to offset the income hit.

When does California claim tax on RSU vests?

California taxes RSU income based on where you LIVED while the shares vested — not where you live when you sell. If you vested $200k of RSUs while a California resident and then moved to Texas before selling, California still taxes the original vest income.

California's Franchise Tax Board (FTB) is unusually aggressive about pursuing residents who relocate after large vest events. If you're planning a move with significant unvested RSUs, talking to a tax professional about timing is genuinely worth the cost.

Frequently asked questions

How are RSUs taxed in California?
RSUs are taxed twice: (1) at vesting, the full market value becomes ordinary W-2 income, taxed at your normal federal and California brackets. (2) At sale, any appreciation since vest is a capital gain — federal preferential rates (0/15/20%) apply, but California taxes the gain at ordinary income rates.
Why is my RSU withholding only 22%?
Your employer uses the federal supplemental wage rate of 22% for RSU sell-to-cover. This works for incomes in the 22-24% federal bracket but under-withholds significantly for higher earners (32%, 35%, 37% brackets). Most California RSU recipients making $200k+ owe additional tax at year-end.
How much will I owe at tax time on my RSU vest?
Depends on the gap between the 22% federal default and your true marginal rate. At $200k+ base salary, expect 8-15% of the vest value to be unaccounted for in default withholding. On a $100k RSU vest, that's $8,000-$15,000 owed at year-end.
Should I sell RSUs immediately after vesting?
Selling immediately means zero capital gain or loss — vest price equals sale price, no additional tax beyond the ordinary income at vest. If you hold and the stock rises, the gain is taxable; if it falls, it's a loss. Selling immediately removes this risk and is a common diversification strategy.
Does California tax RSU vests if I move to Texas after?
Yes, for income vested while you were a California resident. California claims tax on the full vest event regardless of when you sell. Moving to a no-tax state after vesting protects future capital gains but not the vesting income itself.
Can I avoid taxes on RSUs?
No legal strategy eliminates the income tax at vest — it's ordinary W-2 income. You can defer some federal tax by maxing pre-tax 401(k), HSA, and other tax-advantaged accounts in the same year. You can manage capital gains timing on subsequent sales. But the vest itself is taxable when it happens.
What's the difference between RSUs and stock options for taxes?
RSUs are taxed as ordinary income at vest. Non-qualified stock options (NSOs) are taxed as ordinary income when exercised on the spread between strike and current price. Incentive stock options (ISOs) have more complex tax treatment with potential AMT implications. RSUs are simpler — vest equals income, no exercise required.
How does sell-to-cover work?
When your shares vest, the brokerage automatically sells enough shares to cover the default tax withholding (typically 22% federal + 10.23% California + FICA + SDI = ~41% combined). You receive the remaining ~60% as actual shares in your account. The cash from the sold shares goes to the IRS and FTB.

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