A new retiree with appreciated investments may have a year when the federal tax rate on some long-term gains is 0%. That does not mean selling is costless: capital gains can change Social Security taxation, Medicare income-related premiums and state taxes. Before the end of 2026, test the entire tax return rather than treating a published 0% bracket as a trading instruction.
Key takeaway
For 2026, the IRS lists a $49,450 taxable-income ceiling for the 0% long-term capital-gain rate for single filers and $98,900 for married couples filing jointly. The ceiling is based on taxable income, not the amount in your brokerage account. Ordinary income uses up room first; other tax and benefit consequences can still apply.
What is capital-gains harvesting?
In this context, harvesting means deliberately realizing a gain on an appreciated asset held in a taxable account during a year with room in a favorable tax bracket. Unlike loss harvesting, the goal is to recognize a gain, potentially reset basis if you repurchase, and reduce future taxable appreciation. Whether that is sensible depends on transaction costs, investment risk and the entire tax picture. It is not something to do in an IRA or Roth IRA simply because this year's capital-gain threshold looks attractive: their tax treatment is different.
The IRS capital gains and losses guide explains that the gain generally equals proceeds less adjusted basis; most investment assets held for more than one year generate long-term rather than short-term gains. The 0% rate generally applies to qualifying net long-term gains within the relevant taxable-income band, not to every kind of investment profit. Collectibles and certain real-estate gains have special rates; short-term gains generally face ordinary-income treatment. The precise ordering on a tax return matters, especially with capital losses and qualified dividends.
The 2026 thresholds come from IRS Revenue Procedure 2025-32, section 4.03: $49,450 for single filers, $98,900 for joint filers and $66,200 for heads of household. Those are maximum 0% rate taxable-income amounts. They are not gross-income exclusions and not a promise that every dollar of gain under the threshold avoids all federal tax effects.
Check the right number
Do not compare your entire sale proceeds with the 0% ceiling. Use projected 2026 taxable income, including other taxable income and qualifying gain, after applicable deductions and tax-return rules. Have a tax professional calculate your actual remaining 0% room.
An example: the sale is not the gain
Suppose a married couple filing jointly has $70,000 of projected taxable income before realizing an additional long-term gain, with no other preferential-rate income. Ignoring interactions for this illustration, the distance to the published $98,900 threshold is $28,900. A taxable brokerage holding worth $90,000 with a $60,000 adjusted basis has an unrealized $30,000 gain. Selling all of it could place $28,900 of the additional gain in the 0% federal band and $1,100 above that band, assuming no other changes. That is an illustration of rate stacking, not a calculated tax bill.
If the couple instead sells enough units to realize $15,000 of gain, the sale proceeds will generally be more than $15,000 because they include basis. Identify specific lots and confirm the broker's records; taxes are based on gain, not cash withdrawn. If an earlier loss carryforward offsets the gain or dividends use up 0% space, the picture changes. Estimate both before-sale and after-sale returns with the same assumptions, rather than assuming the arithmetic above survives actual tax preparation.
The trade-off is not always “harvest as much as possible.” A sale can alter portfolio allocations, create transaction frictions or consume a tax window that you would rather use for a Roth conversion. Selling and repurchasing the same security to recognize a gain is generally different from the wash-sale restriction on losses, but check investment, broker and tax specifics before using any same-day strategy. We are not recommending a security or a transaction.
Social Security can make 0% more complicated
For people already receiving Social Security, realized gains can increase the measure commonly called combined income and cause more benefits to be included in taxable income. Combined income generally adds adjusted gross income, tax-exempt interest and half of Social Security benefits. The Social Security Administration explains that federal benefit taxation may begin when combined income exceeds $25,000 for an individual or $32,000 for a joint filer. Those thresholds are not the capital-gains thresholds. Even if some additional long-term gain lands at a 0% preferential rate, it may increase taxable benefits and the ordinary-income portion of your tax bill.
Consider a retiree whose taxable benefits are already near a transition point. An additional $8,000 gain may not simply add $8,000 to taxable income; the taxable Social Security component could also rise. Do not apply a flat formula without your benefit amount and other income. Conversely, a person who is not receiving Social Security yet would not have that particular current-year interaction. For more on this separate mechanism, see how Social Security is taxed.
A 0% rate is not zero total tax
Check potential taxable Social Security, state income tax, the net investment income tax if applicable, and changes to income-based deductions or credits. Federal capital-gain tax on a particular dollar can be zero while another part of the return changes.
The Medicare two-year lookback
For Medicare beneficiaries, income-related monthly adjustment amounts (IRMAA) generally use tax-return income from two years earlier. IRMAA modified adjusted gross income is generally adjusted gross income plus tax-exempt interest, distinct from taxable income and Social Security combined income. A 2026 realized gain may therefore matter for 2028 premiums. The one-time gain or its disappearance is not itself an SSA-qualifying life-changing event for an IRMAA redetermination; retirement/work stoppage or another qualifying event might support a new determination if its conditions are met. Do not use projected 2028 brackets as settled legal thresholds today. Check the applicable year's premiums and brackets when announced; an estimate is only a scenario input.
Say a couple's 2026 tax return shows $180,000 of Medicare-relevant income before a sale, and a proposed gain adds $25,000. Their post-sale figure might be $205,000 before other interactions. Those round numbers are invented and do not identify a specific IRMAA tier or surcharge: the actual calculation requires tax-return details, filing status and the 2028 schedule. Read what counts for IRMAA for the income definition, then have your adviser model the effect of the exact sale.
If you are retiring this year, also compare tax years. A 2026 partial-year wage income may make 2027 a better year for gain recognition; a future RMD or pension may make it worse. The timing decision is about lifetime after-tax results, not winning a single headline rate in isolation.
How harvesting compares with a Roth conversion
Harvesting a gain in a taxable brokerage account and converting part of a traditional IRA to Roth are different transactions. A conversion generally adds ordinary taxable income in the conversion year; the gain from a qualifying taxable investment sale may face a preferential rate. Both can affect Social Security taxation and Medicare-related income. If you have limited low-bracket room, doing both without coordination may cause one to push the other into a less attractive range.
For example, if a household has $20,000 of estimated room before the 0% gain ceiling, an extra $20,000 of taxable ordinary conversion income could use that entire space before the planned gain. The actual ordering, deductions and tax calculation require tax software or professional review; the point is to compare competing uses of room, not to conclude that a conversion is always inferior. See our retirement income tax strategy for broader withdrawal sequencing.
Checklist for an October-to-December review
- Get accurate basis. Download your brokerage cost-basis and tax-lot information. Confirm holding periods and any carryforward losses with prior returns.
- Project the whole 2026 return. Include wages, IRA withdrawals, pensions, taxable interest, dividends, Social Security and any other realized gains. Estimate the deduction you actually qualify for.
- Compare three scenarios. Calculate no sale, partial gain recognition and a larger gain. Check federal tax, state tax, potential Social Security effects and later Medicare income exposure.
- Check deadlines and settlement. Work with your brokerage and tax adviser on when a taxable sale counts in the 2026 tax year; do not rely on a last-minute order without confirmation.
- Document the decision. Keep the lot selection, confirmation and revised basis records. Revisit withholding or estimated payments if the projected total tax changes.
There is no general rule that a retiree must harvest gains every year. A sale may undermine diversification or trigger costs; a future stepped-up basis under applicable law may change estate considerations. If the asset is needed for upcoming expenses, the right comparison may be a planned withdrawal rather than a round-trip trade. Get individualized tax and investment guidance before making a material sale.
Using Bullseye to frame, not calculate, the trade
Bullseye tracks brokerage balances and projects federal and state taxes, Social Security taxation and Medicare IRMAA within its retirement scenarios. It does not select securities or tax lots, execute trades, determine your legal eligibility for a particular tax rate, or automatically calculate a capital-gains-harvesting transaction. Use an external tax return projection for the sale and its effects first. Then manually enter reasonable income, asset and expense assumptions in alternative Bullseye scenarios and compare longer-term cash flow using the retirement tax planning page as a starting point.
Write down what you changed in each scenario. A baseline with no realized gain, a conservative sale scenario, and a higher-income stress case are more informative than one supposedly optimal number. A plan is useful when it shows what happens if assumptions are wrong; it does not replace an accountant's 2026 return calculation or an investment adviser's judgment about portfolio risk.
Bottom line
For a 2026 gain-harvesting decision, establish actual tax lots, estimate the whole return and compare after-tax outcomes, including possible 2028 Medicare consequences. The published 0% band is a starting point, not a free pass or a recommendation to sell. Consult a qualified tax professional when the stakes are material.
Sources and scope: IRS Revenue Procedure 2025-32 (2026 thresholds), IRS Topic 409 (capital gains and holding periods) and SSA guidance on benefit taxation (accessed October 26, 2026). General education only; tax and investment advice require individual facts.
