That's not quite true. There are discontinuities in that neighborhood, most notably AMT. When you hit that, it affects the calculation of the entire tax bill.

That's not quite true. There are discontinuities in that neighborhood, most notably AMT. When you hit that, it affects the calculation of the entire tax bill. Your point is generally correct, but at this specific point (and a few others, depending on specific circumstances) there are odd effects that come into play. Of course, if you're trying to make a political point, one can focus on those discontinuities to make all kinds of not-generally-true claims.