The US IRS ruled all so called ''digital currency'' as personal property -- other world governments will most likely rule similarly.

Exchanges of personal property are not money transactions and any fluctuation in the personal property's value is subject to taxes. The accounting expense for small volumes would be prohibitive.

As example: if a Dollar or Euro you accept changes in its exchange value, and it is gained in commerce and not in FX trading, the change in value creates no tax liability of profit or loss.