Roth Conversion vs. Capital Gain Harvesting (2026)

Roth conversion vs capital gain harvesting comes down to one shared constraint: both moves draw ordinary income and long-term gains from the same finite low-bracket room in a single tax year. Conversion income stacks first and long-term gains stack on top, so a large conversion can push otherwise tax-free gains into the 15% band. Most retirees cannot fully use both levers at once, so the real question is how to split the room.

Last reviewed: August 2026 | Written and reviewed by Craig Wear, CFP®, founder of Q3 Advisors

Why can’t you fully do a Roth conversion and harvest 0% gains in the same year?

You cannot fully do both because a Roth conversion and 0% capital gain harvesting compete for the same low-bracket room. Under the Internal Revenue Code, conversion income (ordinary) fills the brackets first, and long-term gains stack on top. In 2026 the 0% gains ceiling is $49,450 taxable income for single filers and $98,900 for married couples filing jointly. Every conversion dollar consumes room a 0% gain could have used.

The table below compares the two levers side by side, because the choice is rarely about which is a better idea in the abstract and usually about which one should fill this year’s limited bracket room.

How does the stacking order work: ordinary income first, gains on top?

The code taxes ordinary income (wages, pensions, IRA distributions, and Roth conversions) first, filling the 10%, 12%, and higher brackets from the bottom. Long-term capital gains and qualified dividends are then layered on top to decide which gains rate applies. The 0% long-term rate reaches only gains that fall below the 2026 ceiling ($49,450 single, $98,900 joint) once ordinary income already sits underneath them.

Because a Roth conversion is ordinary income, it lands in the stack beneath your gains. Above the 0% ceiling the gains rate steps to 15%, and to 20% only above $545,500 single or $613,700 joint. Conversion income is not itself net investment income, though it can raise the MAGI that exposes gains to the 3.8% surtax.

Why does a Roth conversion push would-be 0% gains into the 15% band?

A Roth conversion pushes would-be 0% gains into the 15% band because conversion income counts underneath your gains, raising the floor they stack on without lifting the ceiling. Suppose a married couple has $0 taxable ordinary income and $60,000 of long-term gains sitting entirely at 0%. Convert $50,000 and taxable ordinary income becomes $50,000, so only $48,900 of gain ($98,900 minus $50,000) stays at 0% and the rest jumps to 15%.

This is the mechanical heart of the tradeoff. Our companion explainer on Roth conversion and capital gains stacking walks through the stacking math in more depth; this page focuses on the downstream decision of which lever should claim the room.

What is the capital gains bump zone and how much does it cost?

The capital gains bump zone is the range where an extra dollar of ordinary income (such as a Roth conversion) both taxes that dollar and displaces a previously 0% long-term gain into the 15% band. In the 12% ordinary bracket the marginal cost is roughly 27%: 12% on the conversion dollar plus 15% on the gain it bumps. That hidden rate is why over-converting can quietly cost more than the headline bracket suggests.

When does converting first win in a deep low-income year?

Converting first tends to win in a deep low-income year when a retiree faces meaningful future required minimum distributions. Converting at 10% or 12% today can replace ordinary income that would otherwise land at 22% to 32% once RMDs and Social Security begin. The larger the traditional balance and the longer the runway before age 73, the wider the rate gap a conversion can capture and lock in.

What is the conversion arbitrage: today’s 12% versus future 22% to 32% RMD-era rates?

The conversion arbitrage is the spread between today’s rate and the rate you would otherwise pay later. Converting at 12% now instead of paying 24% on a future RMD saves about 12 percentage points, roughly $1,200 per $10,000 converted; against a future 32% rate the spread nears 20 points, about $2,000 per $10,000. These illustrative figures ignore growth, and tax-free compounding inside the Roth typically adds more. The Roth conversion break-even analysis covers the mechanics.

How big do future RMDs have to be to favor conversion?

There is no single threshold, but RMD pressure is the trigger. RMDs start at age 73, and the first-year Uniform Lifetime Table divisor of 26.5 makes the first distribution about 3.8% of the prior year-end balance. A $1,000,000 traditional IRA produces a first RMD near $37,700; a $2,000,000 balance, near $75,500. When projected RMDs plus Social Security are likely to exceed the 0% ceiling or reach the 22% bracket, conversion has the stronger claim.

Projected required minimum distributions for 2026 help gauge that pressure. Note that the RMD age rises to 75 for those born in 1960 or later, so the earliest age-75 RMD year is 2035, extending the low-bracket runway for younger retirees.

Why accelerate conversions before Social Security and RMDs start?

The years between retirement and the start of Social Security and RMDs are often the lowest-income window a retiree will ever see. Many households treat that gap as a limited runway to convert at low rates, deciding how much to convert to Roth each year so no single year is forced into a high bracket. Once benefits and distributions switch on, that low-bracket room narrows sharply and permanently.

When does harvesting 0% gains win instead?

Harvesting 0% gains tends to win when future RMDs are modest and the priority is resetting cost basis at no tax. Because the 0% gains rate versus a future 15% rate is a 15-point spread, harvesting inside the 0% band can, dollar for dollar, carry a wider rate arbitrage than a conversion filling the 12% ordinary bracket. Harvesting also creates no future RMDs, since taxable gains are never subject to them.

Why is the 0%-vs-15% harvest spread sometimes wider than the conversion spread?

Filling the 12% ordinary bracket with a conversion captures roughly a 10-point spread over a future 22% rate. Harvesting a gain at 0% and repurchasing to reset basis captures a 15-point spread over a future 15% rate. On pure rate arbitrage the harvest is wider. The catch: a harvest only resets basis, while a conversion moves dollars into an account whose future growth is never taxed, which can outweigh the narrower spread.

Do small projected RMDs and a big taxable account favor harvesting?

Yes, that profile often favors harvesting. If projected RMDs are small (a modest traditional balance) the future ordinary rate you are trying to avoid may already be low, shrinking the conversion’s arbitrage. Meanwhile a large taxable brokerage account with embedded gains offers real 0% harvesting value, especially to diversify a concentrated position. Many investors in that situation lean toward harvesting, subject to one important step-up caution.

That caution is the forfeited step-up. If an appreciated asset would otherwise be held until death, heirs receive a full basis step-up that erases the embedded gain entirely. Harvesting that same asset now resets a basis heirs would have had reset for free, so a gain that could have passed untaxed is realized for no lasting benefit. Harvesting tends to make more sense on assets likely to be sold during your lifetime, not those earmarked for heirs.

Does harvesting actually dodge the Social Security torpedo, IRMAA, or ACA subsidies?

No. A common myth holds that harvesting sidesteps the income thresholds a conversion trips, but both realized gains and conversion income raise provisional income for Social Security taxation and MAGI for IRMAA and ACA premium tax credits. Each move can trigger the same downstream costs. The honest framing is not which lever avoids the thresholds, but which buys more long-run value per dollar of that shared cost.

How do you split the bracket room between both?

You split the bracket room by deciding how much of the space below the 0% gains ceiling ($98,900 joint) to fill with conversion versus harvest. Because that ceiling sits just below the top of the 12% ordinary bracket ($100,800 joint in 2026), a common approach converts part of the room at 10% to 12%, harvests the rest at 0%, and stops harvesting at the ceiling because gains above it would be 15%.

Worked example: converting part and harvesting the rest in 2026

Consider an illustrative married couple, both 66 and retired, sitting in 2026 before Social Security and RMDs, with $10,000 of other ordinary income. Their 2026 deductions total $47,500: the $32,200 standard deduction, the age-65 additional amount ($1,650 per spouse), and the OBBBA senior deduction of $6,000 per person (P.L. 119-21, available 2025 through 2028). This hypothetical is for education only and is not a projected result.

The couple both converts and harvests, but neither lever is maxed: the $80,000 conversion and the $56,400 harvest together consume one shared pool of low-bracket room.

A year-by-year decision checklist

The right split between converting and harvesting is not a one-time decision; it shifts every year as account balances grow, income sources switch on, and inflation moves the bracket thresholds. Because last year’s answer can be wrong this year, many planners rerun the same short list of factors each year before deciding how much room goes to each lever.

1. Size of projected RMDs and the traditional balance driving them.
2. Years of low-income runway before Social Security and RMDs begin.
3. Social Security claiming timing and provisional-income headroom.
4. IRMAA MAGI position and the two-year lookback (the last conversion year not affecting a premium is age 62).
5. Whether appreciated assets are likely to be held until death (step-up) or sold sooner.
6. ACA premium-tax-credit exposure if either spouse is under 65 and on marketplace coverage.
7. How much of this year’s bracket room a conversion versus a harvest would consume.

How do you sequence conversions and harvests across multiple low-income years?

You sequence them by modeling the whole low-income window rather than optimizing a single year. Some years may tilt toward conversion, others toward harvesting, as balances and thresholds move. Meeting the annual Roth conversion deadline of December 31 matters because a conversion is irreversible and cannot be undone later, and you cannot convert an RMD once distributions begin. Planning the full runway is where much of the value tends to sit.

Frequently asked questions

Can you do a Roth conversion and harvest capital gains in the same year?

Yes, but rarely to the full extent of both, because they compete for the same low-bracket room. Conversion income (ordinary) fills the brackets first and long-term gains stack on top, so a large conversion leaves little or no 0% room for harvesting. In practice most retirees split the space below the 2026 0% ceiling ($98,900 joint) between the two rather than maxing either.

Does a Roth conversion count as ordinary income or capital gains?

A Roth conversion counts as ordinary income, not capital gains. The converted amount is added to taxable income and taxed at ordinary rates (10% to 37% in 2026), the same treatment as an IRA distribution. It fills the brackets beneath your long-term gains, which is exactly why a conversion can push otherwise 0% gains into the 15% band. A conversion is uncapped, irreversible, and due by December 31.

How much capital gains can I harvest at 0% in 2026?

In 2026 the 0% long-term gains ceiling is $49,450 of taxable income for single filers and $98,900 for married couples filing jointly. Other ordinary income fills that space first. The table shows approximate tax-free gain room at $0 and $30,000 of other taxable income (already net of the standard deduction of $16,100 single or $32,200 joint).

Do Roth conversions push capital gains into a higher tax bracket?

Yes. Because conversion income stacks beneath your long-term gains, each conversion dollar raises the floor gains sit on and can displace them from the 0% band into 15%. The conversion does not raise the 0% ceiling; it consumes the room beneath it. In the 12% ordinary bracket the marginal cost of that displacement is roughly 27%: 12% on the conversion dollar plus 15% on the bumped gain.

Is tax gain harvesting better than a Roth conversion?

Neither is universally better; it depends on projected RMDs and goals. Harvesting can carry a wider rate spread (0% versus a future 15%) and creates no future RMDs, favoring retirees with small traditional balances and large taxable accounts. A conversion shelters all future growth tax-free and reduces future RMDs, favoring those with large IRAs and a long runway. Many households coordinate both rather than choosing one.

Do capital gains count toward the 0% bracket before or after ordinary income?

Capital gains are counted after ordinary income. The Internal Revenue Code fills the ordinary brackets first with wages, pensions, IRA distributions, and Roth conversions, then stacks long-term gains and qualified dividends on top to determine the gains rate. Only gain that falls below the 2026 ceiling ($49,450 single, $98,900 joint) once ordinary income sits underneath it qualifies for the 0% rate.

Are there RMDs on capital gains?

No. Required minimum distributions apply to pre-tax retirement accounts such as traditional IRAs and 401(k)s, beginning at age 73 (age 75 for those born in 1960 or later, so 2035 is the earliest age-75 RMD year). Assets in a taxable brokerage account, including embedded or harvested long-term gains, are never subject to RMDs, which is one reason harvesting appeals to retirees with modest IRA balances.

Does harvesting capital gains affect IRMAA or Social Security taxes?

Yes. Realized long-term gains raise MAGI for IRMAA and provisional income for Social Security taxation, just as a Roth conversion does. The 2026 first IRMAA tier begins above $109,000 single or $218,000 joint MAGI (two-year lookback) and is a cliff. Both moves can also raise the 3.8% net investment income tax exposure above $200,000 single or $250,000 joint MAGI, so harvesting is not a way around these thresholds.