37% is the highest federal marginal tax rate. It starts at $510,301, which might kick in for a decent number of Uber shareholders at IPO.
That's also the tax rate, not the withholding rate.
I have no idea what they meant by "but likely need to pay a lot more than that yourself," unless that was a reference to state income tax. 37% is the highest bracket. It's higher than AMT. I'm not sure under what circumstances you'd owe more than 37%.
