It's likely that the taxable event would occur when you can control the bitcoins. For instance, many pools have a minimum payout and you can't withdraw any unti

It's likely that the taxable event would occur when you can control the bitcoins. For instance, many pools have a minimum payout and you can't withdraw any until you meet that minimum. Based on other IRS rules, the taxable event would occur when you reach that withdrawal minimum. As for the exchange to use for the value, it would probably be legitimate to use an average of a few exchanges, if the prices are wildly divergent.