&gt;If we were to impose some cap on income (say $1B&#x2F;year) would it suddenly be &quot;exploitative&quot; to charge any income tax?<p>Maybe not at $1B&#x2F;year (that marginal dollar is damn near infinitesimal at that point).  But maybe if the cap was, say, $50K (or in that rough ballpark) a year characterizing income tax as exploitative could be a concept worthy of exploring.  Especially if we are talking about taking 40% their usable income or more as the article is proposing for the poor assuming they are expecting them to work 8 hours a day.