Tax-Loss Harvesting for Early Retirees: Offset Gains and Build Carry-Forwards

Tax-gain harvesting gets the elegant play. Tax-loss harvesting gets the volume — it's the most widely used tax optimization in taxable portfolios, and for FIRE investors with hundreds of thousands in a taxable brokerage account, it's one of the most reliable ways to reduce the lifetime tax drag on a 30–50 year withdrawal plan.

The strategy: deliberately sell an investment at a loss to realize that loss on paper. Use it to offset capital gains you've realized, and if losses exceed gains, deduct up to $3,000 per year from ordinary income. Any remaining losses carry forward indefinitely — building a "tax asset" that offsets future gains for years.

How tax-loss harvesting works

When you sell an investment for less than you paid (your cost basis), the difference is a realized capital loss.¹ Capital losses offset capital gains dollar-for-dollar. The rules:

• Same-character offset first. Short-term losses first offset short-term gains (taxed as ordinary income). Long-term losses first offset long-term gains (taxed at 0%, 15%, or 20%). Then remaining losses from one category cross over to offset the other.
• Net loss deduction. If total losses exceed total gains, the excess reduces your ordinary income by up to $3,000 per year ($1,500 if married filing separately).²
• Carry-forward. Losses beyond the $3,000 annual cap carry forward indefinitely, preserving their short-term or long-term character to future years.³

Tax-loss harvesting calculator

Enter your losses being harvested and any capital gains already realized this year. The calculator shows your gain offset, tax savings, and carry-forward.

The wash-sale rule: the #1 trap to avoid

If you sell a security at a loss and buy the same or a "substantially identical" security within 30 calendar days before or after the sale — a 61-day window — the loss is disallowed under the wash-sale rule (IRC § 1091).⁴ The loss doesn't disappear; it's added to the cost basis of the replacement security. But it won't help you this tax year, defeating the purpose of harvesting.

ETF pair strategy for maintaining market exposure

The most common technique for FIRE investors: sell a losing ETF and immediately buy a different ETF covering similar (but not identical) market exposure. You stay invested with similar return characteristics; the loss is realized and the wash-sale clock runs on the replacement.

Important caveat: The IRS has not definitively ruled on whether ETFs from different providers tracking the same underlying index constitute "substantially identical" securities.⁵ Most practitioners use same-index/different-provider pairs (VTI ↔ SCHB), but this is not guaranteed safe. The safest approach is to harvest into a genuinely different fund — different index, different exposure — and wait 31+ days before switching back if desired.

FIRE-specific angles

Large taxable accounts amplify the value

The FIRE community's approach — high savings rate, early accumulation — often concentrates years of investment returns in a taxable brokerage account. A $1M position in VTI with a $600K cost basis has $400K in unrealized gains. In a 15% correction, that same position might drop to $850K — with losses harvestable at the lots purchased at higher prices. The mechanics: identify specific lots (not average cost) and sell the highest-cost lots to maximize the realized loss while keeping overall market exposure via a replacement ETF.

Market downturns are harvesting events

For an accumulation-phase FIRE saver, a 20% market correction is financially painful but creates a harvesting opportunity proportional to the portfolio size. Harvesting $50,000 in losses from a $500K portfolio and immediately rebuying into a similar fund:

• Maintains your full market exposure
• Generates a tax asset worth $7,500 at 15% LTCG rate (or $11,000 at 22% ordinary income rate) over time
• Resets your cost basis upward on the replacement lots

The harvesting doesn't require the market to stay down — you've locked in the tax benefit, and the replacement fund captures the recovery identically to what you sold.

ACA MAGI coordination

Capital losses reduce your net capital gain included in AGI — which flows directly into MAGI for ACA premium tax credit purposes.⁶ If you're on a marketplace plan and anticipate capital gains from rebalancing, harvesting losses in the same year can keep your MAGI below the ACA subsidy cliff (~$63,840 single / $86,640 MFJ for 2026). This matters most in years when you're already near the cliff from Roth conversions or other income.

Carry-forward is a compounding tax asset

A $50,000 loss carry-forward in your Schedule D isn't just a deferred $3,000/year deduction — it's $50,000 of future gains that can be realized entirely tax-free. If you're in accumulation and harvest that carry-forward in retirement when you're selling rebalancing lots at 15%, the carry-forward is worth $7,500. If you're doing aggressive Roth conversions and use the carry-forward to shelter a rebalancing sale, that's $7,500 in preserved cash flow over time. Don't treat it as a slow-burn $3,000/year deduction — build it when markets drop and deploy it when gains are unavoidable.

How to execute a harvest

1. Identify losing lots. In your brokerage tax center, find positions with unrealized losses, specifically lots with higher purchase prices than current market value. Use lot-level view, not average cost.
2. Check your 61-day window. Confirm you haven't purchased the same security in the 30 days before the sale date. Mark your calendar for 31 days after the sale if you want to rebuy the original fund.
3. Sell the specific lots. Use specific lot identification (not FIFO or average cost basis) when placing the sell order. Some brokerages require you to select this in the order screen or settings.
4. Immediately rebuy a replacement. Buy a different-but-similar fund or ETF. You stay fully invested; the replacement position's new holding period starts fresh.
5. Track the carry-forward. The unused loss appears on Schedule D (lines 6 and 14 for short-term and long-term respectively) and automatically rolls forward to the next tax year on your Schedule D.