Trading is taxed just like capital gains, and mining as income. For small investments with few trades, it's straightforward and you can likely use a free service. Beyond a certain threshold (like 200 trades), it's probably worth using something like https://bitcoin.tax/ or https://cointracking.info/ which will create your forms for you after you import (and painstakingly correct) trades, at a rather steep price ($120/mo) though cointracking has a lifetime buy for $380...