Bracketing isn't the only mechanism for progressive taxation at play. There's also EIC, child tax credit, AMT, and a whole zoo of other exemptions and credits a

Bracketing isn't the only mechanism for progressive taxation at play. There's also EIC, child tax credit, AMT, and a whole zoo of other exemptions and credits and deductions, etc. Not to mention that the only reason a lookup is being used is to reduce opportunity for error in hand-calculating one's tax obligation. And it's also another big reason the current tax system doesn't fit on a post card: A pretty big chunk of the instruction booklet is those tax tables.