Typical comp shape
Mobile engineer (iOS / Android)s usually earn rsu + espp. Common employers include Apple, Meta, Uber, DoorDash. Apple mobile hires often stack ESPP on top of RSUs, which stretches concentration in employer stock.
What California changes
In California, every RSU vest, NSO exercise, and ESPP purchase carries 13.3% state tax on top of federal. For a senior mobile engineer (ios / android) with $300k+ of equity income, the state layer routinely adds $25-45k to the annual bill.
State AMT for ISO holders
If your mobile engineer (ios / android) role grants ISOs (common at pre-IPO startups, uncommon at post-IPO mega-caps), be aware that California runs its own AMT calculation. An ISO exercise-and-hold here generates AMT at two layers, not one.
Planning cadence
For a mobile engineer (ios / android) in California, the three planning windows are: after each RSU vest (withholding check and sell-vs-hold), before any ISO exercise (AMT model at both federal and state), and in Q4 (estimated tax top-up to clear the safe harbor).