You must declare the value of the token at the time you receive it from your pool or you receive it in your wallet. However if you are running your mining operation as a business you only need to declare the net value at the time the token was received. Value of token at the time of receipt minus the cost to produce it. Just like a real physical gold miner does. Then later if you sell the token and it has increased or decreased in value from the time of receipt you need to report the capital gain or loss.
what about instamining and solo mining, where i mine coin that have no value long before i'll sell them? what i declare at first, they don't have any value...gold miner also don't have instamining with altcoin...
also how can someone keep track of all his shitcoin, i think it's too much hassle, if you keep your money in the alt, youa re free from taxation, and you need only to declare the amount spent on electricity