There is – the income bracket isn’t what all your money is taxed at. It’s a graduated scale. I’m going to make up numbers here just for an example.
I make $125,000. The first $5000 has no tax on it. The next $20000 are taxed at 5%. The next $25,000 are 10%. The next $30,000 is taxed at 15%. The next $30000 is taxed at 20%. And the last $15,000 are taxed at 35%.
So my total tax is 20000(0.05) + 25000(0.1) + 30000(0.15) + 30000(0.2) + 15000(0.35) = $19,250. My effective tax is 15.4%, even though I’m taxed higher than that on $45000 of my $125000.
It’s a piecewise function basically. And it works really well here because you start getting into very discretionary spending when it gets high, you’re not buying the essentials. You could have a bracket that has 75% tax on everything above a million for instance, and poorer people would be completely unaffected. This is why the myth of “if I get a raise I’ll be in a higher bracket and pay more in taxes” is incorrect.