I had an interesting experience with FTB... I returned to WA without changing jobs, after working in CA and getting some ISOs. The way it works is that you separate the income from the ISOs that don't meet holding reqs proportionally between certain dates. I.e. you pay CA taxes on the fraction of "wage" income earned in CA vs another state; and no CA taxes on the other portion, attributable to that other state. However, there's no form for that; so, for a few years I'd do the math in Excel, and then send FTB a form that looks like "here's my total income, and I pinkie swear this (much smaller) random-looking number is my CA income".
What's interesting is sometimes I was too lazy to do proper math for some small sale transactions that were few days apart, so I'd round it in favor of FTB. And every year FTB would charge me as expected, and then send me a check for $20, $50 or whatever, presumably because of that.
In short, I'm pretty sure FTB knows everything about you and your CA taxes :)
Also based on reading the publications myself (disclaimer: IANAL), I'm pretty sure unless you actually work/live in CA, or have delayed income based in CA, you are not generally supposed to pay CA taxes.
What's interesting is sometimes I was too lazy to do proper math for some small sale transactions that were few days apart, so I'd round it in favor of FTB. And every year FTB would charge me as expected, and then send me a check for $20, $50 or whatever, presumably because of that.
In short, I'm pretty sure FTB knows everything about you and your CA taxes :)
Also based on reading the publications myself (disclaimer: IANAL), I'm pretty sure unless you actually work/live in CA, or have delayed income based in CA, you are not generally supposed to pay CA taxes.