&gt;The best possible tax scheme for poor people would be a simple flat tax that is impossible for rich people to avoid.<p>You&#x27;re looking at the wrong end of the telescope.  It&#x27;s really not that difficult to look at a tax table and cross-reference your income, so a flat tax is a very minor improvement.<p>Where every tax system gets tripped up is in determining what qualifies as income.  People who manage to avoid taxes aren&#x27;t somehow lowering their rates; they&#x27;re getting inflows of money excluded from the &quot;income&quot; accounting box.<p>It&#x27;s not an easy problem to deal with, either - states have been trying for centuries.  Most of the write-offs individuals and corporations take are perfectly reasonable for some situations and very much abused in others.  As you try to prevent abuse you end up with a tax code that&#x27;s so complicated there are more ambiguous &quot;gray areas&quot; for people to take advantage.