0% Capital Gains Harvesting Calculator

By Tom, CPA · Updated October 25, 2026

TL;DR: The 0% long-term capital gains rate applies until taxable income reaches $49,450 single or $98,900 married filing jointly in 2026. This calculator subtracts your ordinary taxable income and gains already realized to show how much more gain you can harvest at 0%.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Find out how much gain you can realize for exactly zero federal dollars. Gain harvesting means selling appreciated investments in a taxable account and buying them back to raise your cost basis, at a 0% rate. There is no wash sale rule for gains, so you can repurchase immediately.

The hard part is knowing how much room you have. That is what this tool computes.

CPA Warning Label: Zero federal tax is not zero consequences. Harvested gains raise AGI, which can cut ACA credits, make Social Security taxable and cost state tax.

Inputs explained

• Filing status: 1 single, 2 married filing jointly.
• Ordinary income: everything taxed at regular rates: IRA withdrawals, Roth conversions, pensions, interest, non-qualified dividends, short-term gains, taxable Social Security.
• Gains already realized: qualified dividends and net long-term gains you already have this year, including fund distributions you expect in December.
• Extra deduction: age-65 additional deduction, senior deduction or itemized deductions above the standard deduction.

How the 0% room is computed

Step 1: ordinary taxable income = ordinary income minus deductions (not below zero). Step 2: any deduction left over because ordinary income was smaller also shelters gains. Step 3: total 0% capacity = leftover deduction + (0% threshold − ordinary taxable income). Step 4: subtract gains already realized. The result is how much more long-term gain you can realize at 0%.

2026 thresholds: $49,450 single, $98,900 married filing jointly; standard deductions $16,100 and $32,200 (IRS Rev. Proc. 2025-32 as amended).

Interaction with ordinary income

Ordinary income comes first. Each extra dollar of ordinary income, such as a Roth conversion, reduces the 0% room by a dollar. That is why gain harvesting and Roth conversions compete for the same space (see gain harvesting vs Roth conversion). If ordinary taxable income is already above the threshold, the room is zero.

Exceeding the room is not a disaster: only the excess is taxed at 15%. But if the excess is unplanned, you paid tax you could have avoided by waiting until January.

Examples

Illustration 1. Married, $60,000 of IRA withdrawals, no gains yet. Ordinary taxable income $27,800. 0% room: $71,100. Federal tax after harvesting it: $2,840, the same as before.

Illustration 2. Single, $10,000 of ordinary income and $5,000 of gains already. The $6,100 of unused deduction plus the full $49,450 threshold gives total capacity of $55,550. Additional room: $50,550. Tax: $0.

Illustration 3. Married, $140,000 of ordinary income. Ordinary taxable income $107,800 is above $98,900. Room: $0.

State tax caveat

Most states tax capital gains as ordinary income and have no 0% rate. A $70,000 harvest can be federally free and still cost a few thousand dollars of state tax. States without an income tax avoid this. Check your state before harvesting large amounts.

Why harvest at all?

Harvesting does not reduce your portfolio's value; it resets your cost basis upward. Later, when you sell to fund spending in a higher-income year, there is less gain to tax. It also creates flexibility: a high-basis taxable account can fund living expenses with little taxable income, which helps keep MAGI low for ACA credits. For investors who will leave assets to heirs, the step-up in basis at death may make harvesting less valuable, but most early retirees will spend at least part of their taxable account during their lifetime.

Repeat the calculation every year. The thresholds rise with inflation, your income changes, and fund distributions arrive whether you invited them or not. A good habit is to run it once in November, after funds publish distribution estimates, and harvest in early December, leaving a cushion of a few thousand dollars for surprises.

Mechanics of a harvest

1. Pick lots with the largest long-term gains (held more than one year).
2. Sell enough to realize the target gain, using specific lot identification.
3. Repurchase the same fund immediately, or a similar one.
4. Record the new basis and holding period start date; the new lots will be short-term for a year.

Other limits

• Harvested gains raise MAGI for ACA premium tax credits and IRMAA, and provisional income for Social Security.
• Only long-term gains (held more than one year) qualify; short-term gains are ordinary income.
• Ignores NIIT, credits and AMT. Head of household is not modeled.
• Defaults are examples.

Lavish Larry harvested on December 31 without checking a fund's distribution, and found out in February. Frugal Fran ran this calculator in November and left a buffer.