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California · iso amt

ISO exercises and AMT in California

California runs its own state-level AMT on top of federal AMT. Exercising ISOs here costs more than in most states; we walk through the full stack.

What California residents actually pay

California taxes ordinary income at a top marginal rate of 13.3%. RSU settlement value, NSO exercise spread, and ESPP discount income all count as ordinary wages for this purpose and flow through the state's normal brackets.

Calculates its own state AMT; one of the most expensive states for ISO exercise.

Federal AMT on the bargain element

Exercising ISOs and holding the shares creates AMT "preference income" equal to the spread between fair market value at exercise and your strike price. That's the bargain element. It doesn't show up on a W-2, and many people discover it only when their CPA calculates AMT in April.

California's separate state AMT

California runs its own AMT calculation layered on top of federal. An ISO exercise that triggers federal AMT typically triggers state AMT too; the rate stacks. Plan cashless exercise-and-sell versus hold carefully.

Frequently asked

Does California tax RSU income the same as wages?
Yes. California treats RSU ordinary income as wages, taxable at the state's top marginal rate of 13.3%. Supplemental-wage federal withholding (22%, or 37% above $1M YTD) does not adjust for state withholding, so you often owe extra at filing.
What happens if I exercise ISOs while living in California?
California calculates its own AMT on top of federal AMT, so large ISO exercises can trigger two AMT bills. Plan the disqualifying-vs-qualifying disposition decision with both layers in mind.
I moved to California from another state. Who taxes my vesting RSUs?
Most high-tax states (CA, NY, MA) source RSU ordinary income to workdays between grant and vest. If your grant pre-dates your California move, expect the old state to tax the portion of each tranche attributable to workdays earned there. California taxes the remainder.
Can I reduce California taxes by timing my RSU sales?
California taxes long-term capital gains at the same rate as ordinary income, so timing alone does not produce a state savings — only federal. Holding for 12 months still halves the federal rate on gains above basis.

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