Originally Posted by Atticus

Because it is a tiered tax system and doesnt jump from 10 to 40%. For simplicity sake we'll use real basic numbers. Say you make $50k and 0-$25k is taxed at 10% and $26k to $50k is taxed at 20%. So far you've paid $7500 in taxes. If the next $25k ($51k to $75k) of earnings rises to 30% instead of the 20% the $26k to $50k in earnings were taxed you're paying an additional $2500 in tax ($7500 versus $5000).

So if someone decides there not going to work anymore (but have the ability and time) to make $25k more in earnings and pocket an additional $17500 after tax just because the tax rate went up an additional 10% for that tier they're either an idiot or lazy.

A tiered system might not be fair but to use it as an excuse to not work is ridiculous.