Comment: Re:It has to be? (Score 1) 381
Except that's not how the net worth is calculated for tax purposes. Otherwise, nothing would be taxable. Even ordinary employees labor for dollars of equal value.
When you trade A for B (whether A is labor, or B is labor, or A is dollars, or B is Bitcoins, or B is beer, or whatever) your change in net worth is calculated by what you got minus what you gave. But the value of what you gave is not the fair market value. It's the *lower* of the fair market value or what it cost you to get it. (Called your "basis".)
This means if you buy some stock, or Bitcoins, or wine for $50 and its value goes up to $500, that's not taxable. But if you sell it for $500, your profit is $500 minus the lower of $500 or $50, hence $500 - $50, and thus $450.
So if you barter, say, a paint job for a trailer, your profit for tax purposes is the fair market value of the trailer less what it cost you to provide the paint job. Sadly, if you bought a car for $35,000 and then traded it something after its value dropped to $8,000, $35,000 is not your basis. (Too bad, because that would be a great tax evasion strategy) $8,000 is, because that's lower.