You don't seem to understand how the progressive taxation works. In U.S. you pay 0 tax on first ~20k income, 15% on the next 35k, 22% on next 40k and so on (random numbers). The 22% is what you pay on anything above 55k in this example. But for the first 55k you pay only 20k * 0% + 35k * 15%=5250, e.g. 9.5%