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California · rsu tax

RSU taxes in California: withholding, supplemental wages, and state nexus

How California's 13.3% top marginal rate interacts with supplemental-wage withholding on RSU vesting, and what to do when your RSUs vest after a move.

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.

Withholding gap

Federal supplemental-wage withholding on RSU vesting is flat — 22%, rising to 37% once year-to-date supplemental wages exceed $1M. If your actual marginal rate is higher, the shortfall shows up at filing. In California, layer on 13.3% at the top and model what you'll owe before year-end.

Sourcing when you move

If you earned part of a vesting tranche while in a different state, most high-tax states (California, New York, Massachusetts) use workday allocation between grant and vest. Your payroll will likely withhold only for your current state, so a manual true-up at filing is the rule, not the exception.

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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