When people evade income taxes by not declaring taxable income, a vicious cycle results  Tax evasion forces lawmakers to raise income tax rates, which causes the tax burden on nonevading taxpayers to become heavier
This, in turn, encourages even more taxpayers to evade income taxes by hiding taxable income
No one who routinely hides some taxable income can be induced by a lowering of tax rates to stop hiding such income unless fines for evaders are raised at the same time.