In general, trading cryptocurrencies is very similar to trading in stock or other securities when it comes to your taxes. You must report on your tax return any gain or loss realized from trading in a virtual currency that has a value in real currency or that can act as a substitute for real currency.
Go to this section in Credit Karma Tax: Capital Gains
Your brokerage or exchange may have provided you with a Form 1099-B but even if they didn’t you may still need to report your cryptocurrency transactions and the realized gain/loss. It is very important to maintain accurate records of any transactions including dates acquired, dates sold, purchase price, and sale price.
Source: irs.gov
The IRS provides guidance on Virtual Currencies if you need more information to help understand your situation.
What if I mined cryptocurrency like Bitcoin?
If you mined cryptocurrency for yourself, you’ll need to report it as income at its fair market value on the day you acquired it. If you’re a self-employed miner, you can deduct operating expenses from your mined cryptocurrency income, but you may also be subject to self employment tax. You’ll need to keep accurate records of your activities so you can accurately report your income.
Go to this section in Credit Karma Tax: Other Income
If you were paid to produce cryptocurrency for someone else, the amount you were paid should appear on either your Form W-2 if you were an employee. if you were an independent contractor, you should have received a Form 1099-MISC.
Source: irs.gov