i.e. - I build a fence for a farmer, and he gives me 7 goats.
What do I owe the IRS?
The IRS does not accept payment in goats. They could secure a court order requiring you to sell the goat, or allowing them to sell the goat to satisfy your tax liability (with the excess returned to you).
http://en.wikipedia.org/wiki/Taxation_of_illegal_income_in_t...
> The Internal Revenue Code is not a mechanism for enforcing other codes of law, such as criminal law. [2] A person’s taxable income will generally be subject to the same Federal income tax rules, regardless of whether the income was obtained legally or illegally.
Also, Yale Law has a PDF entitled "Taxing Income from Unlawful Activities" (1974):
http://digitalcommons.law.yale.edu/cgi/viewcontent.cgi?artic...
> When income from unlawful activities is reported, the taxpayer often supplies his name, address, and net income (usually in round figures, with such laconic labels as "miscellaneous income" or "income from various sources") and leaves the rest of the return blank.
The whole PDF is actually a very interesting historical study of the ins and outs of taxing ill-gotten gains.
I think you know this, but perhaps not all readers do: you still are actually required to pay tax on earnings in BTC - just not declaring the income is illegal (and the authorities _are_ likely to notice if you're making a large amount of it and converting it back to your home currency to spend).