Assuming there isn’t a 2nd income drastically raising your income, why wouldn’t the company withhold the right percentage, considering they know what you make? Choosing a flat 22% seems odd.
If you speak with a tax professional, for which I am not, they would tell you to calculate the difference and pay quarterly amounts. In practice this means that I sell more periodically just for taxes[2].
1. https://www.irs.gov/filing/federal-income-tax-rates-and-brac... 2. https://www.irs.gov/businesses/small-businesses-self-employe...
Edit: from what I understand payroll isn't informing Schwab of your current bracket, nor do I think they should have to.
I do need to do something weird with my taxes every year to enter that the taxes were already paid, as by default when I import, it shows that I need to pay taxes on the whole thing. Every year it feels like doing it for the first time; it’s always confusing to find the right spot in TurboTax and which numbers to enter for the taxes I already paid.
If the brokerage is doing the deduction based on a checkbox the user selects, I can see how a discrepancy could arise.
It may be better for you. For example, you may want to cover the rest of the tax bill by selling other shares and doing tax lost harvesting. You may think your company is going to the moon and decide to cover the rest of your tax bill with cash and keep your shares (this is usually a bad idea). The way they do it gives you flexibility.