Sweden:
We have a 30% tax on our trading profits.
And also on mining from what I understood when I called then it's 50% of the profit. So you are allowed to payoff the price for the equipment and energy used without taxing but after that they want 50%... :/
As someone mentioned this is only when you convert it to fiat.
It also applies when you trade between cryptocurrencies, you calculate the SEK value and pay/deduct based on the profit/loss.
See 'Exempel - växling mellan kryptovalutor':
https://www.skatteverket.se/privat/skatter/vardepapper/andratillgangar/kryptovalutor.4.15532c7b1442f256bae11b60.html