Do the long-term capital gains brackets stack on top of my ordinary income?

Yes, and this trips up a lot of people. Long-term capital gains and qualified dividends are taxed in their own 0%/15%/20% brackets, but those brackets sit on top of your ordinary income, not beside it. The IRS first fills the stack with wages, interest, and other ordinary income, then layers capital gains on top. So a $50,000 salary can push what would have been 0%-rate gains up into the 15% zone. This is why a low-income or gap year is so valuable for harvesting gains cheaply: less ordinary income underneath means more room in the 0% capital-gains bracket above it. The thresholds adjust yearly for inflation, per the IRS. Model your stack with the Capital Gains Calculator at wealthserene.com/tools/capital-gains before you sell.