Individual buyers and sellers enter details on Form 8949 (Sales and Other Dispositions of Capital Assets) which then feeds a summary to Schedule D (Capital Gains and Losses). Short term net gain is taxed at 0%, 10%, 15%, 25%, 28%, 33%, 35%, or 39.6%, and long term net gain is taxed at 0%, 15%, or 20%, both depending upon one's income. Individual miners use Schedule C (Profit or Loss From Business) and Schedule SE (Self-Employment Tax) for their mining rewards and mining expenses. The net profit is taxed at 0%, 10%, 15%, 25%, 28%, 33%, 35%, or 39.6% depending upon one's income, while self employment tax could be as high as an additional 18.2%.

Businesses I'm sure have different forms.