For tax purposes one of the key concepts in mining Bitcoin and trading Bitcoin is the use of a third party. If you have moved coin to a third party to execute a trade and the IRS audits you, it's up to you to prove that these addresses are owned by third parties.
So then you need to supply the entities individual or corporate name. If you're lying and cannot produce the identity of the exchanger, then you're going to be a world of trouble. Even if it's a decentralized exchange, you're going to need to show the transaction that execute the trade.
Even if you're doing these trades with shielded Zcash transactions (these are completely anonymous transactions) once you supply addresses A, B, C, etc... to the IRS (or the ATO in my case) and you get audited, you need to show who these third parties are.
Honestly, cryptocurrency is not an issue for the tax office, even cryptocurrency such as Zcash and Monero are not an issue.