Tax efficiency in investing comes down to managing where your assets live and when you realize gains. Long-term capital gains on assets held more than one year are taxed at 0%, 15%, or 20% federally, while short-term gains are taxed as ordinary income. This creates a strong incentive to hold investments for at least a year. The 0% LTCG bracket applies when total taxable income, including gains, stays under roughly $47,000 single or $94,000 MFJ in 2024, which is useful for early retirees and December tax-gain-harvesting opportunities. Qualified dividends from most U.S. large-cap stocks held for the required period receive long-term capital gains treatment; non-qualified dividends from REITs, MLPs, and short-held positions are taxed as ordinary income and are best held in tax-advantaged accounts.
Tax-loss harvesting lets you sell a losing position, immediately buy a similar (but not "substantially identical") security, and book the loss. Capital losses first offset capital gains one-for-one, then up to $3,000 of ordinary income per year, with any excess carrying forward indefinitely. The wash-sale rule disallows the loss if you buy a substantially identical security within 30 days before or after the sale; the rule extends to your spouse's accounts and to IRA repurchases, where the loss is permanently disallowed. Practically, swapping an S&P 500 ETF for a total-market fund avoids the wash sale while keeping comparable market exposure; hold the alternative through day 31, then swap back if desired. Direct indexing extends harvesting to single-stock level inside an index portfolio, enabling more losses per year for high-net-worth investors with concentrated positions.
Asset location — placing tax-inefficient assets in tax-advantaged accounts and tax-efficient assets in taxable accounts — amplifies returns. Bonds and REITs, which generate interest and non-qualified dividends taxed at ordinary rates, belong in 401(k)s and IRAs. Broad stock index funds, with low turnover and qualified dividends, are appropriate for taxable accounts. International stock funds often belong in taxable accounts too, because foreign tax withheld on dividends can be claimed as a U.S. foreign tax credit — a benefit wasted inside retirement accounts. Above $200,000 of income ($250,000 MFJ), the 3.8% Net Investment Income Tax applies to dividends, interest, capital gains, and rents. Finally, step-up basis at death resets inherited stocks' and bonds' cost basis to the date-of-death value, so heirs sell with no capital gain on prior appreciation — a powerful nudge to evaluate inherited positions fresh.