Capital Gain Harvesting Windows

Most investors focus on avoiding taxes when they sell—but the bigger opportunity is deliberately selling winners when the tax bill is zero. The 0% long-term capital gains bracket lets you realize gains, reset your cost basis higher, and reduce future tax liability—all without paying a dime in federal capital gains tax. For 2025, that bracket covers up to $48,350 in taxable income for single filers and $96,700 for married filing jointly (IRS Revenue Procedure 2024-40). The practical antidote to a growing unrealized gain problem isn't hoping for a step-up at death. It's systematically harvesting gains in years when your income leaves room in the 0% bracket.

TL;DR: Capital gain harvesting is the mirror image of tax-loss harvesting—you sell appreciated assets at a gain when your taxable income is low enough to pay 0% federal tax on those gains, then immediately repurchase to reset your cost basis higher. Done correctly, it permanently eliminates tax on the harvested appreciation.

What Capital Gain Harvesting Actually Is (And Why It Works)

Capital gain harvesting is the deliberate realization of long-term capital gains during tax years when your taxable income falls within the 0% long-term capital gains bracket. You sell an appreciated asset, pay no federal capital gains tax, and repurchase the same asset immediately—resetting your cost basis to the current market value.

The point is: you're converting unrealized gains into realized gains at a 0% rate, and your new higher cost basis means less taxable gain when you eventually sell for good.

This works because of three structural features in the tax code:

0% bracket existence → Wash sale rule asymmetry → Immediate repurchase → Basis reset

1. The 0% bracket is real. Long-term capital gains (assets held more than one year) are taxed at 0%, 15%, or 20% depending on taxable income. The 0% rate isn't a loophole—it's the statutory rate for lower-income brackets.

2. The wash sale rule only applies to losses. Under 26 U.S.C. § 1091, the IRS disallows loss deductions if you repurchase substantially identical securities within 30 days. But this rule does not apply to gains. You can sell at a gain and buy the same asset back the next second.

3. The basis resets permanently. Your new cost basis equals the sale price. That reset doesn't expire or reverse (unless the tax code itself changes).

The 0% Bracket: Know Your Numbers

You can't harvest gains effectively without knowing the exact bracket thresholds. Here are the current numbers from IRS Revenue Procedures:

2025 Long-Term Capital Gains Brackets

2026 Long-Term Capital Gains Brackets (IRS Rev. Proc. 2025-32)

Standard Deductions (These Expand Your Harvesting Room)

Why this matters: The 0% threshold applies to taxable income, which is AGI minus your deduction. A single filer with no other income in 2025 could have up to $63,350 in gross income ($48,350 bracket + $15,000 standard deduction) and still pay 0% on all long-term gains. For a married couple filing jointly, that ceiling is $126,700 ($96,700 + $30,000).

The TCJA decoupled capital gains brackets from ordinary income brackets starting in 2018, and the One Big Beautiful Bill Act of 2025 made these lower brackets permanent. The 0% MFJ threshold has expanded from roughly $77,200 in 2018 to $96,700 in 2025—a steadily growing harvesting window.

Worked Example: A Retired Couple Fills the 0% Bracket

Here's how this works in practice with real numbers.

Phase 1: The Setup (November 2025)

Marcus and Dana, married filing jointly, are both 63 and recently retired. Their 2025 income consists of:

• Pension income: $40,000
• Interest and dividends: $8,000
• Total gross income: $48,000

They take the standard deduction of $30,000 (MFJ, 2025).

• Taxable income before any gain harvesting: $18,000 ($48,000 − $30,000)

Their brokerage account holds a broad-market ETF purchased years ago for $80,000, now worth $160,000—an $80,000 unrealized long-term gain.

Phase 2: The Calculation (How Much to Harvest)

The 0% LTCG threshold for MFJ in 2025 is $96,700. Marcus and Dana's taxable income is $18,000 before gains.

Maximum 0% harvest = $96,700 − $18,000 = $78,700

They can realize up to $78,700 in long-term capital gains at 0% federal tax.

Phase 3: The Execution

They sell $78,700 worth of their ETF's appreciation (selling shares worth approximately $157,400 with a cost basis of roughly $78,700). The next day, they repurchase the same ETF at market price.

Results:

The practical point: Marcus and Dana hold the same investment, in the same amount, but their cost basis jumped by $78,700. If they eventually sell those shares in the 15% bracket, they've permanently avoided $11,805 in federal tax. At the 20% bracket, the savings would be $15,740. And they paid nothing to achieve this.

Mechanical alternative: If they had done nothing, that $78,700 in gains would remain unrealized—eventually taxed at 15% or 20% when they sell, or possibly eliminated by a step-up in basis at death. But relying on the step-up is a bet on dying before needing the money (not exactly a financial plan).

The NIIT Guardrail (Don't Ignore the 3.8% Surtax)

The 0% capital gains bracket is only part of the equation. The Net Investment Income Tax adds a 3.8% surtax on net investment income when MAGI exceeds $200,000 (single) or $250,000 (MFJ) (IRS Topic No. 559).

The test: Will your MAGI—including the harvested gains—stay below the NIIT threshold?

These thresholds have never been indexed for inflation since the NIIT was introduced in 2013. Each year, bracket creep captures more taxpayers. Even if you're comfortably in the 0% capital gains bracket, a large harvest that pushes MAGI above the NIIT ceiling creates a 3.8% cost you didn't plan for.

The point is: run the NIIT check before you run the 0% bracket calculation. A harvest that saves 15% in future capital gains tax but triggers 3.8% NIIT today may still be worthwhile—but you need to model it, not discover it at filing time.

Hidden Tripwires Beyond Federal Tax

Gain harvesting looks clean on the federal return, but realized gains increase your Modified Adjusted Gross Income. That ripple effect creates costs in places most investors don't check.

State income tax. Eight states impose no income tax on capital gains (AK, FL, NV, NH, SD, TN, TX, WY). Washington state taxes long-term gains above $250,000 at 7%. In every other state, your "0% federal" harvest may still generate state tax ranging from 0% to 13.3%. A California resident harvesting $50,000 in gains at 0% federal still owes California's rate on those gains.

ACA premium tax credits. Realized capital gains increase MAGI, which can reduce Affordable Care Act premium subsidies. Under current law (extended through the One Big Beautiful Bill Act), there is no hard cliff at 400% of FPL — subsidies phase out gradually on a sliding scale. But a large harvest that significantly increases your MAGI can still reduce your premium credits meaningfully, potentially offsetting the tax savings.

Medicare IRMAA surcharges. Capital gains pushing MAGI above $106,000 (single) or $212,000 (MFJ) in 2025 can trigger Income-Related Monthly Adjustment Amount surcharges on Medicare Part B and Part D premiums. IRMAA uses a two-year lookback, so gains harvested in 2025 affect premiums in 2027.

The rule that survives: federal capital gains tax is just one line item. The total cost of a harvest includes state tax, lost subsidies, and increased Medicare premiums. Model all three before executing.

When Harvesting Windows Open Widest

Not every year offers the same opportunity. Certain life events create unusually large 0% bracket space:

• Early retirement before Social Security begins. Earned income drops to near zero, leaving the entire 0% bracket available for gains.
• Gap years between jobs. A year of reduced income (sabbatical, career change, parental leave) opens temporary bracket space.
• Years with large deductions. Unusually high medical expenses, charitable contributions, or business losses can compress taxable income, expanding harvesting room.
• Economic downturns. During COVID-19 in 2020–2021, many taxpayers experienced reduced earned income from furloughs and business closures. The 2020 0% threshold was $40,000 (single) / $80,000 (MFJ)—and financial advisors widely recommended gain harvesting during those low-income years.

The point is: gain harvesting is opportunistic. The best windows are temporary. If you wait for a "better" time, the window may close before you act.

Coordinating with Tax-Loss Harvesting and Roth Conversions

Gain harvesting doesn't exist in isolation. It interacts directly with two other strategies.

Tax-loss harvesting. Losses offset gains dollar for dollar. If you have $20,000 in harvested losses carried forward and you realize $20,000 in gains, those gains are fully offset—even outside the 0% bracket. The annual net capital loss deduction limit is $3,000 ($1,500 for married filing separately), with unlimited carryforward for excess losses (IRS Topic No. 409). Coordinate by using loss carryforwards against gains that would otherwise be taxed at 15%+, and reserve the 0% bracket for gains that have no losses to offset them.

Roth conversions. Both Roth conversions and gain harvesting consume taxable income space. If you convert $30,000 from a traditional IRA to a Roth, that $30,000 counts as ordinary income and reduces your remaining 0% bracket room. Sequence matters: calculate your Roth conversion amount first, then fill whatever 0% bracket space remains with gain harvesting (since Roth conversions are taxed as ordinary income at potentially higher rates, they get priority for low-bracket space).

Year-End Gain Harvesting Checklist

Essential (High ROI)

• Calculate projected taxable income for the year (wages + pensions + Social Security + other income − deductions). If at least $1,000 below the 0% LTCG threshold, you have a harvesting window.
• Identify long-term lots with the largest unrealized gains. Only assets held over 365 days qualify for long-term rates.
• Run the NIIT check. Confirm that MAGI including harvested gains stays below $200,000 (single) or $250,000 (MFJ).
• Check state tax liability. Determine your state's capital gains rate before assuming the harvest is "free."

High-Impact (Workflow)

• Model ACA and IRMAA effects. If you receive ACA subsidies or are on Medicare, calculate the MAGI impact before executing.
• Coordinate with Roth conversions. Allocate low-bracket space to Roth conversions first (ordinary income rates), then fill remaining space with gain harvesting.
• Repurchase immediately. The wash sale rule does not apply to gains—buy back the same asset right away to maintain your allocation and reset cost basis.
• Document your new cost basis. Confirm your brokerage updated the basis on repurchased shares. Keep records of the sale and repurchase for tax filing.

Optional (Good for Early Retirees and High-Net-Worth Investors)

• Project multi-year harvest schedules. If your unrealized gains exceed one year's 0% bracket, plan harvests across multiple low-income years.
• Review qualified dividends. Qualified dividends use the same 0% bracket—account for expected dividend income when calculating remaining bracket space.
• Evaluate asset location. Prioritize holding high-growth assets in taxable accounts (where gain harvesting is possible) and bonds in tax-advantaged accounts.

Your Next Step

This week: Pull up your brokerage account and run one number. Take your projected 2026 gross income, subtract the standard deduction ($16,100 single / $32,200 MFJ), and compare the result to the 0% threshold ($49,450 single / $98,900 MFJ). The gap between your taxable income and that threshold is your harvesting window. If it's greater than zero, you have gains to harvest before December 31.

This article is for educational purposes only and does not constitute personalized financial or tax advice. Consult a qualified tax professional before implementing any gain-harvesting strategy. Tax laws and thresholds are subject to change. Sources: IRS Topic No. 409, IRS Revenue Procedure 2024-40, IRS Revenue Procedure 2025-32, IRS Topic No. 559, 26 U.S.C. § 1091, Tax Foundation 2025 Tax Brackets.