If you got rid of a cryptocurrency or used it by exchanging it on an exchange or when buying goods and services, you will owe taxes if the realized value is higher than the price at which you purchased the cryptocurrency. You may have a taxable capital gain at short- or long-term rates. You have to pay taxes on cryptocurrencies. The IRS classifies cryptocurrencies as property, and cryptocurrency transactions are subject to tax by law just like transactions related to any other property.
If you earn cryptocurrencies through mining, you receive them as a promotion or as payment for goods or services, they are counted as regular taxable income. You must pay taxes on the full value of the cryptocurrency the day you receive it, based on your marginal income tax rate.