If you're vesting enough equity, your brokerage is only holding on to 22% and you don't have enough of your salary withheld, it's very possible to end up with a

If you're vesting enough equity, your brokerage is only holding on to 22% and you don't have enough of your salary withheld, it's very possible to end up with a marginal rate that is in the high 20s or low 30s, and not enough tax paid. This can happen without triggering the 110% of previous year portion if you're regularly vesting a lot of equity - the more you vest, the farther 22% is going to be from your actual marginal tax rate. I used single quotes instead of double quotes around "just handled" to quote the idea and summary of what you were saying - that it would be handled automatically by the brokerage - and not as a direct quote