Mining, trading or earning bitcoin should not be subject to any taxes in any country, but some countries are already reviewing on how to apply applicable taxes on it. Taxes should only be applied to your bitcoin earnings once you converted it to a fiat currency because that is the only time that it can be classified as an income on your part.

It will be quite hard to compute the taxes since it is a decentralized currency and records on how much you acquired the coin might not be available and also your expenses on mining should also be computed first.