You can't just assess a basis for bringing the coin into existence, and I don't know how you can. Both things are constantly fluctuating each day; the value of coin you are holding while trying to mine it, and the amount of electricity it finally takes to get the coin.
So I mine all this week and get three 0.01 BTC deposits. Are you saying that I have to record the basis for each 0.01 BTC, so I'll have a basis value that I have to keep track of with *EACH AND EVERY* time the pool makes a 0.01 BTC deposit to my wallet? That's horrendous, but you see how the issue is it could take 3 days or 5 days of mining electricity to achieve that 0.01 BTC deposit. Then it's complicated by the fact that I would also have to make note of the particular value of that 0.01 BTC deposit at the time of the deposit.
That's the only way I can see this being possible. You would have to, with each BTC deposit into your wallet, note the instantaneous dollar value of the deposit, and subtract the amount of electricity it took to get that deposit. Maybe I'm missing something, but is there an easier way to establish the basis for coins that you mine?
I agree for buying/selling, that's easy as pie. The issue is for mining. How do you establish the basis for coins you mined out of thin air? We know it costs electricity, but the issue is the mining is spread out over weeks and weeks of fluctuation in how long it takes to mine a particular fraction of a coin, how much electricity that fraction costs, and how you incorporate the fluctuating value of BTC at the time that fraction was deposited into your wallet.