That's when you buy it. I'm not an accountant, but AFAIK if someone gave you stock for performing a service you would pay taxes on it at that point in time. Then if you sold it you would pay taxes on the difference in value.
I think the key might be that the IRS is viewing bitcoin as a payment for the service of mining.
I think the key might be that the IRS is viewing bitcoin as a payment for the service of mining.