There is no case law on this, however a litigation is in progress by Jarrett demanding a refund from the Internal Revenue Service (IRS) of the USA claiming that the cryptos mined by the Plaintiffs and held by them would not be taxable. However, I have attached a link above which contains the Plaint relating to the refund of Income Tax already paid.

The Code relating to Income is, gross income minus the permitted deductions. The mining and possessing of the crypto coins are includible in the gross income as per the Code.

The argument forwarded is that these coins did NOT exist but were generated through the work and therefore created. On the basis of which the cryptos in the hands of the Plaintiff cannot be treated as income, till the same is paid out for some goods or services or converted into a Fiat currency.
The persuasive analogy is taken from a case law where the cake baked by a baker cannot be taxed as the baker had created the cake and till sold and the value realised, the cake would be a property created, rather an asset created but the value of which has not been realised and hence not an income. Further, it is argued that the “coming in” would be an income and in this case, the Plaintiff claims he has merely created an asset for which certain expenses had been incurred, therefore, there has been a “going out” than a coming in.

It would be interesting to watch the verdict on this case.

More so because, the IRS would lose track of who mined how much in which year if the arguments of the Plaintiffs are to be accepted in toto.
Secondly, if those mined crypto coins are used in subsequent years for some goods or services, how would the IRS know that these cryptos had been realised in value, unless there has been a compelling reporting mechanism for the year of generation and a statement of assertion by the Assessee that the crypto is still with him under his control?

Supposing, the Assessee asserts that he had lost the secret password to the place of storage in the internet, what would be his liability? If the Assessee were to somehow retrieve after many years the password, how would be be able to bring into accounting the lost cryptos? What if a person gets undeclared remuneration for generating cryptos and ‘sells’ it to an investor, who retains it without a trace in the blockchain and later declares it as having mined by him? Should the Government give MINER’S LICENSE?

Either way, the decision in this case is likely to spawn many further issues, which would compel the US government to bring in stricter reporting requirements as regards mining of cryptos.