It works the same as regular tax brackets. The first $80k (cool that it's a nice round number in 2020) is taxed at 0% and then amounts above that up to $496,600 is taxed at 15%. Note that other sources of income (earned income, tax deferred withdrawals, pensions, some social security, dividends, short term gains) also count, and the standard deduction (and other deductions) reduces gross income to arrive at taxable income. So say you had $94,800 of other income then you could only realize $10k of long term capital gains at 0% becuase $104,800 - $24,800 standard deduction = $80k.