There was a recent case involving the imposition of inheritance taxes on artwork that, because it contains bald eagle feathers, cannot be sold to pay the taxes. So theoretically the result of that case could give us some idea of how the courts would treat a situation where someone solely had bitcoin income but no way to exchange it. Plus, there is a certain amount of US-centric moaning in this thread (and I am not criticizing eurleif). Just because the US says "no" doesn't mean that another country won't say "yes." And in that case bitcoin can be converted to that country's currency and then back to USD.