Well, I asked a similar question to this here --->
https://bitcointalk.org/index.php?topic=1060307.0The answers will be different from country to country, based on their own tax laws and regulations. I am also intriqued by this and wonder how they will solve this problem.
They would most probably define it as digital currency under the current tax legislation {PayPal etc...}
^^^That.
It all depends on where you are located and how Bitcoin is seen - is considered - there.
In U.S. it is considered property.
On the other hand there are countries that do not consider it at all.