Tax Loss Harvesting: When, How, and How Much It Saves
Tax loss harvesting saves the average investor $1,000–$3,000 per year in taxes, and high earners with taxable accounts in volatile markets can see far more. The strategy is straightforward: you sell investments at a loss, use those losses to offset gains (and up to $3,000 of ordinary income annually), then buy back into a similar position. Done consistently, it's one of the highest-leverage tax moves available to a DIY investor.
What Tax Loss Harvesting Actually Does to Your Tax Bill
Tax loss harvesting (TLH) reduces taxable income by realizing paper losses in your taxable brokerage account. The IRS lets you use capital losses to offset capital gains dollar-for-dollar, then deduct up to $3,000 of remaining losses against ordinary income each year, carrying any unused losses forward indefinitely.
Here's the core formula: Tax Savings = Harvested Loss x Your Marginal Tax Rate.
Say you harvest $20,000 in losses and you're in the 22% ordinary income bracket with a 15% long-term capital gains rate. If those losses offset $20,000 of short-term gains (taxed as ordinary income), you save $4,400 in federal taxes that year. If they offset long-term gains instead, you save $3,000. The difference matters, which is why timing and gain type both affect your actual result.
Two important boundaries: TLH only works in taxable accounts. Your 401(k), IRA, and Roth IRA don't generate taxable gains or losses, so there's nothing to harvest. And losses don't disappear if you don't use them this year, they carry forward indefinitely, which makes early harvesting especially powerful.
Step 1: Identify Which Positions Are Harvestable
A harvestable loss is a position currently worth less than your cost basis (what you paid, including reinvested dividends). Most brokerages show this in your account under "unrealized gain/loss." Focus on positions that are:
- Down at least 5–10% from your cost basis (smaller losses rarely justify the transaction friction)
- Held in a taxable account
- Not within 30 days of a recent purchase of the same or "substantially identical" security (the wash-sale rule)
Example: You bought 50 shares of a total U.S. stock market ETF at $200/share ($10,000 total). It's now at $170/share ($8,500). Your harvestable loss is $1,500.
Check your full holdings list quarterly at minimum. During a market correction of 10% or more, do it immediately. The losses are only real for tax purposes if you actually sell. A position that drops 15% and then recovers gives you zero tax benefit if you waited.
Step 2: Execute the Sale and Avoid the Wash-Sale Rule
The wash-sale rule is the one rule that can invalidate your entire harvest. If you sell a security at a loss and buy the "same or substantially identical" security within 30 days before or after the sale, the IRS disallows the loss. The 30-day window goes both directions.
The fix: Immediately reinvest the proceeds in a similar but not identical fund. Your goal is to stay invested (so you don't miss a market rebound) while sidestepping the wash-sale trap.
Practical substitutions that most tax professionals consider acceptable (though the IRS has not issued a definitive list, so consult your advisor):
- Sell Vanguard Total Stock Market ETF (VTI), buy iShares Core S&P Total U.S. Stock Market ETF (ITOT)
- Sell Vanguard S&P 500 ETF (VOO), buy SPDR S&P 500 ETF Trust (SPY) or iShares Core S&P 500 ETF (IVV)
- Sell a bond fund tracking one index, buy a bond fund tracking a different (but similar) index
After 31 days, you can swap back to your original holding if you prefer it. Your new cost basis in the replacement fund is the price you paid for it, which resets your future gain/loss clock.
One trap people miss: If you hold the same ETF in your IRA or 401(k) and automatically reinvest dividends within that 30-day window, the wash-sale rule can still trigger across accounts.
Step 3: Apply the Losses Against the Right Gains First
The IRS requires you to net losses in a specific order: short-term losses offset short-term gains first, long-term losses offset long-term gains first. After netting within each category, any excess crosses over.
Why this matters: Short-term gains are taxed at ordinary income rates (up to 37% federally in 2026). Long-term gains are taxed at 0%, 15%, or 20% depending on your income. Offsetting short-term gains is almost always worth more.
Formula for prioritizing: Offset short-term gains first, then long-term gains, then ordinary income (up to $3,000/year).
If you have $10,000 of short-term losses and $10,000 of short-term gains, you owe $0 in capital gains tax on those positions regardless of your bracket. If you're in the 32% bracket, that's $3,200 saved on the federal return alone, before state taxes.
Any losses beyond current-year gains carry forward and appear on next year's Schedule D automatically, as long as you file accurately.
Step 4: Quantify Your Real After-Tax Savings
Most investors underestimate TLH's value because they only think about this year's tax bill. The actual benefit compounds over time.
The compounding angle: Money you don't pay in taxes today stays invested. $3,000 in deferred taxes, invested at 7% nominal annual return over 20 years, grows to roughly $11,600. That's the full economic benefit of a single year's $3,000 ordinary income deduction for a 22% bracket investor, not just the $660 tax saving in year one.
Research from Vanguard (2022) estimated that systematic TLH can add 0.5% to 1.5% in after-tax annual returns for investors in higher brackets with volatile, diversified taxable portfolios. Over 30 years, 1% per year of additional after-tax return on a $500,000 portfolio is roughly $471,000 in extra wealth (using $500k growing at 7% vs. 6% nominal over 30 years: $3.81M vs. $2.87M).
For a retirement plan projection, plug your after-tax return assumption into our retirement calculator to see how a 0.5–1% annual improvement affects your end balance.
When TLH Is NOT Worth It (Know the Exceptions)
Tax loss harvesting is not universally beneficial. Skip it, or proceed cautiously, in these situations:
You're in the 0% long-term capital gains bracket. In 2026, single filers with taxable income under roughly $47,025 and married filers under $94,050 pay 0% on long-term gains. If your gains would be taxed at 0% anyway, harvesting losses against them saves nothing.
You expect to be in a much higher bracket in the future. Harvesting now lowers your cost basis in the replacement fund, which means a larger taxable gain when you eventually sell. If your rate rises from 15% to 23.8% (adding the 3.8% Net Investment Income Tax), the deferred gain cost can exceed today's benefit.
Your losses are tiny relative to your portfolio. Transaction costs, tax prep complexity, and the risk of triggering wash-sale violations aren't worth it for a $200 loss on a small position.
You're within 30 days of a dividend distribution in the fund you plan to buy. Buying before an ex-dividend date can create a taxable event that partially offsets your harvest.
The general rule: TLH makes clear financial sense if you're in the 22% ordinary income bracket or higher, you have a meaningful taxable account (above $50,000), and you're harvesting at least $2,000–$5,000 in losses at a time.
Complete Worked Example: $22,000 in Losses, Real Math
The setup: Maya is a software engineer, single, with $180,000 in gross income and roughly $155,000 in taxable income after deductions in 2026. Her federal marginal rate is 24% on ordinary income and 15% on long-term gains. She has a $300,000 taxable brokerage account.
In Q1 2026, a market pullback puts three of her ETF positions underwater:
- Position A: $12,000 unrealized short-term loss (held 8 months)
- Position B: $6,000 unrealized long-term loss (held 14 months)
- Position C: $4,000 unrealized short-term loss (held 4 months)
Total harvestable losses: $22,000
She also has $8,000 in realized short-term gains from earlier in the year (she sold a stock that had risen).
Step-by-step tax impact:
- Short-term losses ($12,000 + $4,000 = $16,000) first offset her $8,000 short-term gain. Remaining short-term losses: $8,000.
- Long-term losses ($6,000) have no long-term gains to offset, so they cross over.
- Total remaining losses: $8,000 (short-term) + $6,000 (long-term) = $14,000, after eliminating the $8,000 gain.
- She deducts $3,000 against ordinary income this year (the annual cap).
- She carries forward $11,000 to 2027.
2026 federal tax savings:
- $8,000 short-term gain eliminated x 24% = $1,920 saved
- $3,000 ordinary income deduction x 24% = $720 saved
- Total 2026 savings: $2,640 federal (plus applicable state tax savings)
2027 carryforward value (if used against short-term gains): $11,000 x 24% = $2,640 in potential additional savings.
Maya immediately reinvests all proceeds into equivalent-but-not-identical ETFs to stay fully invested, avoiding the wash-sale rule. After 31 days, she reviews whether to swap back.
Total two-year tax benefit: up to $5,280 federal, just from one harvest during one market pullback. She keeps that money invested, and at 7% it grows for decades.
Ready to see how this fits your full financial picture? Build your free plan at Rightmont to model your tax strategy alongside your retirement and savings goals in one place.
Try the Calculator
Model how consistent tax-loss harvesting affects your long-term retirement balance using our free retirement calculator at https://rightmont.com/calculators/retirement-calculator, then build a full tax-optimized plan at https://rightmont.com/onboard.
Frequently Asked Questions
How much can tax loss harvesting actually save me?
Tax loss harvesting saves you money equal to your harvested losses multiplied by your marginal tax rate. For example, $10,000 in harvested losses saves a 24% bracket investor $2,400 in federal taxes. Vanguard research estimates systematic harvesting can add 0.5% to 1.5% in after-tax annual returns for higher-bracket investors with sizable taxable accounts.
What is the wash-sale rule for tax loss harvesting?
The wash-sale rule disallows a capital loss if you buy the same or a substantially identical security within 30 days before or after the sale. To avoid it, immediately reinvest in a similar but not identical fund (for example, swap VTI for ITOT), wait 31 days, then swap back if you prefer your original holding.
Can I harvest tax losses in my IRA or 401(k)?
No. Tax loss harvesting only works in taxable brokerage accounts. Retirement accounts like IRAs and 401(k)s don't generate taxable gains or losses because withdrawals are taxed as ordinary income (traditional) or tax-free (Roth), regardless of what happened inside the account.
How often should I do tax loss harvesting?
Review your taxable accounts for harvestable losses at least quarterly, and immediately after any market drop of 10% or more. Most of the value comes from acting quickly during volatility, since positions that recover before you sell generate no tax benefit at all.
What happens to capital losses I can't use this year?
Unused capital losses carry forward indefinitely under IRS rules. They appear automatically on next year's Schedule D and offset future gains or up to $3,000 of ordinary income per year until fully used. There is no expiration date on carried-forward capital losses for individual taxpayers.
Is tax loss harvesting worth it if I'm in a low tax bracket?
Generally not, if your long-term capital gains rate is 0% (which applies to single filers with taxable income under roughly $47,025 in 2026). Harvesting losses to offset gains you'd pay 0% on produces no tax savings. It becomes clearly worthwhile once you're in the 22% ordinary income bracket or higher with a meaningful taxable account.
Related Calculators
Related Scenarios
Related Articles
What decision is on your mind?
Get a confident answer in under 60 seconds. No spreadsheets, no fees.
Model My Decision →