the way tax works, is that only the money that bump you over the threshold is taxed at the higher bracket.

so if there is a bracket up to $100 taxed at 5% and a bracket between $101 to $200 taxed at 10%…

if you made $101 … the first $100 taxed would cost $5. and the tax on the $1 would cost $0.10.

so someone making $100 pays $5 with $95 remaining, and the person making $101 pays $5.10 with $95.90 remaining…

so then there is no reason to deny a raise of any amount, even riding the threshold.