What's the difference between tax-gain and tax-loss harvesting?

Both deliberately realize investment gains or losses to manage taxes, but in opposite directions. Tax-loss harvesting means selling an investment that's down to lock in a capital loss, which offsets capital gains and up to $3,000 of ordinary income per year, with extra losses carried forward. You reinvest in a similar (not "substantially identical") holding to stay in the market and avoid the 30-day wash-sale rule. Tax-gain harvesting is the reverse: in a low-income year, you intentionally sell winners while your long-term capital-gains rate is 0% (taxable income under about $48,350 single / $96,700 joint in 2025), resetting your cost basis higher tax-free. Loss harvesting suits high-income years; gain harvesting suits low-income years like early retirement or a gap year. Model the impact at wealthserene.com/tools/capital-gains.