Simple. If IRS has received an information return from a workplace designating itself your "employer" testifying that you received "wages" (which flow to taxable income), and if you do not give them correct information, your abrogation delegates to them eventually the power to do the assessment themselves instead of having you self-assess; then they can enforce your assessment. All citizens have the sovereign responsibility to read the definitions of the law for themselves and self-assess correctly when there is any question of taxable income.