Tax-Gain Harvesting

Tax-gain harvesting is the deliberate realization of a long-term capital gain in a year when the taxpayer's income is low enough that the gain is taxed at 0% or at an unusually low rate. Published sources also call it simply gain harvesting; the two names describe the same manoeuvre, and the "tax-" prefix exists mostly to mirror tax-loss harvesting, which is its opposite number. Where tax-loss harvesting captures a loss and lowers basis, tax-gain harvesting captures a gain and raises it.

The move is almost always paired with an immediate repurchase, so the investor's holdings are unchanged once the trade settles and only the cost basis has moved. Nothing in the tax code prevents that repurchase, which is the structural feature the whole strategy rests on.

The rule that makes it work is the one that does not exist. Internal Revenue Code section 1091 is headed "Loss from wash sales of stock or securities", and every operative sentence in it disallows a loss where substantially identical stock or securities are acquired within 30 days before or after the sale. There is no parallel provision for gains anywhere in the section, so selling at a gain and rebuying the same fund the same afternoon changes nothing about the tax result. A tax-loss harvester has to find a not-substantially-identical replacement and wait out a 61-day window; a gain harvester has neither problem.

What the strategy buys is basis, and basis is only worth something if the position is later sold at a rate above zero. That makes the case for it narrower than it first appears. If the investor will eventually sell in a year when the gain is again taxed at 0%, harvesting achieved nothing. If the position will instead be held until death, section 1014 resets basis to fair market value anyway and harvesting was unnecessary. The strategy pays where a later sale is likely and likely to be taxed, which typically means someone who expects higher income later, or who will need to sell into a specific goal.

The room is also contested. A year with unusually low taxable income is the same year a Roth conversion wants, and the two compete directly: gain realized at 0% consumes the space that conversion income would otherwise have filled at a low ordinary rate, and vice versa. Only one of them can have it.

Finally, realized gain is income for purposes that do not care what rate it was taxed at. It raises adjusted gross income, which is the measure used for marketplace health insurance premium tax credits in the same year, for Medicare's income-related premium surcharge on a two-year lag, for the formula that decides how much of a Social Security benefit is taxable, and for the base-year income that federal student aid calculations use. A gain taxed at 0% federally can still cost real money through one of those, and state income tax is a separate calculation again: many states tax capital gain as ordinary income with no equivalent zero rate.

The sequence is short. Estimate taxable income for the year before any harvesting, work out how much long-term gain would still be taxed at 0% once ordinary income has stacked underneath it, sell enough of an appreciated lot to realize about that much gain, and repurchase immediately if you want to keep the exposure. The new purchase establishes a new, higher cost basis, and a new holding period for the replacement shares.

A hypothetical. Theo owns 200 shares he bought at $30, a cost basis of $6,000, now worth $70 a share, or $14,000. That is an $8,000 unrealized gain. In a low-income year he sells all 200 shares and buys 200 back the same day at $70. If the whole $8,000 fits under his 0% ceiling, the federal tax on the sale is zero and his basis is now $14,000. Three years later he sells at $90 a share, or $18,000. His taxable gain is $4,000 rather than the $12,000 it would have been without the harvest, and at a 15% rate that is $600 of tax instead of $1,800.

Two practical notes on the same example. The repurchase resets the holding period, so a sale within the next year would be short-term and taxed at ordinary rates. And the round trip costs whatever the bid-ask spread and any commission come to, which on a thinly traded holding can be more than the tax saved.

Pros

• Converts unrealized gain into basis at a rate of zero, which is as cheap as realizing a gain ever gets.
• No replacement security and no waiting period, because the wash sale rule reaches losses only.
• Makes a later rebalancing or a concentrated-position unwind materially cheaper.
• Fits naturally into years that already exist for other reasons: a sabbatical, a career break, or the gap between retiring and starting Social Security.

Cons

• Pointless in a tax-deferred or Roth account, where basis does nothing.
• Achieves nothing if the position would have been sold in another 0% year anyway, or held until death and stepped up under section 1014.
• Consumes a low-income year that a Roth conversion might use to better effect.
• Raises adjusted gross income, which can reduce a premium tax credit, increase Medicare surcharges two years later, make more of a Social Security benefit taxable, or affect financial aid.
• State income tax is calculated separately, and a state may tax the gain even when the federal rate is zero.
• Trading costs and a reset holding period are real, if usually small.