Tax loss harvesting trades a tax break now for a lower cost basis later

Tax loss harvesting means selling an investment at a loss in a taxable brokerage account to offset realized capital gains or, when losses exceed gains, reduce taxable income. Losses can offset short-term or long-term gains; short-term gains are taxed at higher rates. To count for a given year, the sale must occur by December 31st, though opportunities can arise anytime during the year. The income deduction is limited to $3,000 per year for single filers or married couples filing jointly; unused losses carry forward. Growth in US retirement accounts is not taxed, so this strategy does not apply there.

The IRS wash sale rule disallows the loss if a substantially identical security is bought within 30 days before or after the sale. It applies across investment accounts and can be triggered by reinvested dividends or capital gains. The speaker recommends turning off reinvestment, checking purchases in the past 30 days, selling the losing position, then either buying a replacement fund immediately or holding cash for 31 days before repurchasing the original. Turn reinvestment back on afterward unless harvesting more losses. Because the IRS has not explicitly defined ‘substantially identical,’ the speaker favors funds tracking different indexes; an on-screen list of possible swaps is referenced but not specified in the audio [inferred from on-screen list reference]. Staying invested may also avoid missing a handful of strong market days.

In the examples, Sarah offsets a $2,000 short-term gain with a $1,500 loss: at a 24% rate, tax falls from $480 to $120. If that gain were long-term at 15%, tax would fall from $300 to $75. Ashley offsets a $2,000 long-term gain completely with a $2,000 loss; with a $3,000 loss instead, she also deducts $1,000 from income, saving $300 on gains and $150 on income, or $450 total, at the example’s 15% rates. Patrick, a Boglehead-style index-fund investor with no realized gains, harvests $5,000 in losing tax lots, deducts $3,000 from income and carries $2,000 forward. The transcript calls Sarah’s second reduction 60%, although $300 to $75 is 75%.

The speaker cites a first quadrant study estimating that annual harvesting raises final portfolio value by about 14%—$140,000 on a $1 million portfolio. But repurchasing at a lower cost basis can increase taxable gains later: harvesting generally defers tax rather than eliminating it. It may offer little benefit if long-term gains would already be untaxed; the speaker gives annual income below about $40,000 as the threshold at the time of the video. M1 Finance’s tax optimization selling algorithm is noted as selling loss-making tax lots first when shares are sold, not as automatically harvesting losses.