Typical comp shape
Security engineers usually earn rsu + espp. Common employers include Cloudflare, CrowdStrike, Okta.
What Illinois changes
In Illinois, every RSU vest, NSO exercise, and ESPP purchase carries 4.95% state tax on top of federal. For a senior security engineer with $300k+ of equity income, the state layer routinely adds $25-45k to the annual bill.
Planning cadence
For a security engineer in Illinois, the three planning windows are: after each RSU vest (withholding check and sell-vs-hold), before any ISO exercise (AMT model at federal only), and in Q4 (estimated tax top-up to clear the safe harbor).