Tax Loss Harvesting, Explained

A $12,000 investment loss can be worth $2,070 on this year's federal return under one set of assumptions. It can also be worth $0 if a replacement purchase trips the wash-sale rule.

The technique belongs inside a diversified investment plan, not ahead of it. Saving tax does not repair a worse portfolio.

What does tax loss harvesting do?

Selling below tax basis realizes a capital loss. Capital losses first offset capital gains. If net losses remain, federal rules generally allow up to $3,000 against ordinary income, or $1,500 for married people filing separately, and carry the rest forward.

IRS Publication 550 explains the annual limit, carryovers and wash sales. The account statement's red number is not enough. A loss becomes part of the tax return only after a taxable sale and the matching rules are applied.

What is the $12,000 worked example worth?

Assume an investor realizes a $12,000 long-term loss and a $9,000 long-term gain in the same year. Assume the gain would otherwise face a 15% federal rate and the investor is in a 24% marginal ordinary-income bracket. Ignore state tax, net investment income tax and other gains or losses.

If the loss were $16,000 instead, $4,000 would remain after those offsets and generally carry forward. The current-year value would not suddenly include all $16,000.

Why does tax basis decide whether a loss exists?

Basis generally starts with purchase cost and changes with events such as reinvested distributions, returns of capital and prior wash-sale adjustments. The market price can be below last year's high and still be above tax basis, producing a gain rather than a deductible loss.

Choose the actual tax lot. Selling the oldest shares by default may realize a gain while a newer lot holds the intended loss. Brokerage average-cost elections and specific-lot procedures have rules and deadlines, so confirm the selected lot before the trade settles.

Reinvested dividends also add basis. The dividend tax example shows why ignoring those purchases can overstate a later gain.

How does the wash-sale window work?

A wash sale can occur when substantially identical stock or securities are acquired within the period beginning 30 days before the loss sale and ending 30 days after it. That is a 61-day span including the sale date.

The rule can apply to purchases by a spouse and to automatic dividend reinvestment. A tiny recurring purchase can therefore affect part of a carefully planned loss. Pause and inventory recurring trades before selling.

When the replacement is in a taxable account, the disallowed loss is generally added to replacement basis and the holding period carries over. That often defers rather than destroys the deduction. The outcome can be harsher when the replacement purchase occurs in an IRA, because the taxable-account loss may be disallowed without a taxable replacement basis that later restores it.

What does substantially identical mean?

The phrase is intentionally narrower than "similar" and broader than an identical ticker in every possible case. Selling one broad-market fund and buying another fund tracking a different index may reduce risk of a wash sale, but the IRS does not publish a universal ETF substitution list.

Do not invent certainty where the rule has facts and judgment. The cleaner the economic equivalence, the more carefully the transaction needs review.

Do short-term and long-term losses have the same value?

They enter a netting sequence. Short-term gains and losses are combined, long-term gains and losses are combined, and the resulting categories then interact. A short-term loss offsetting a short-term gain can be more valuable than the same loss offsetting a gain eligible for a lower long-term rate.

That means the $2,070 worked example is not a universal value for a $12,000 loss. Change the gain's character or rate and the result changes. Add state tax and the value can rise; add an unused carryforward and the timing can move.

The portfolio still comes first. Use the rebalancing rules to decide what you want to own, then see whether a tax-aware trade can reach that allocation.

When is the effort not worth it?

A $600 loss offsetting a 15% gain has $90 of current federal value. That can disappear into bid-ask spreads, trading restrictions, tax-preparation cost or one bad substitution. The investor also faces market risk while waiting to repurchase.

Harvesting can make sense for a meaningful loss in a taxable account when a suitable replacement keeps the allocation intact. It is less persuasive when it creates a portfolio you would not otherwise own.

What about automated tax loss harvesting?

Automation can monitor opportunities and basis lots more consistently than a person. It cannot see an outside spouse account, an IRA at another custodian or a planned sale unless those data reach the system. It can also generate many small lots and a longer tax record.

Evaluate the after-fee, after-tax value rather than counting harvested losses as investment return. A deferred tax dollar is useful, but it is not an extra dollar of market performance.

Compare any automation fee with a low-cost baseline such as the index fund and ETF structures already available. A permanent percentage fee can outlast the temporary tax benefit.

When this does not apply

Loss harvesting does not create a current capital-loss deduction inside a tax-deferred retirement account. It also does not help when there is no economic loss relative to tax basis, even if the investment is down from a prior high.

If employer stock, options, mutual-fund distributions, crypto transactions or multiple household accounts are involved, coordinate the trades with a qualified tax professional before executing them.

Next steps

1. List every gain, loss, basis lot and scheduled household purchase.
2. Calculate the current tax value under explicit capital-gain and ordinary rates.
3. Choose a replacement that preserves the portfolio without pretending wash-sale judgment is automatic.