Can a Roth Conversion Raise Your Capital Gains Tax? 2026 Guide

A Roth conversion and a sale of an appreciated investment can create different kinds of income. Their tax character remains different, but both can affect the same return.

IRS Publication 590-A says the portion of a Traditional IRA distribution that would have been included in income generally remains included when converted to Roth. IRS Topic 409 explains that net short-term gains are taxed as ordinary income, while qualifying net long-term gains may receive lower rates depending on taxable income. [1] [2]

For a simplified way to visualize the federal calculation, imagine taxable income as a stack. Ordinary taxable income fills the lower portion. Qualified dividends and net long-term capital gains are placed above it. The capital-gains thresholds then determine how much of that upper layer falls into the 0%, 15%, or 20% band. The actual tax return uses the Qualified Dividends and Capital Gain Tax Worksheet or Schedule D Tax Worksheet when applicable. [2] [6]

For 2026, Revenue Procedure 2025-32 lists the maximum 0% capital-gains amounts at $49,450 for single and married-filing-separately returns, $98,900 for married filing jointly and qualifying surviving spouses, and $66,200 for heads of household. The maximum 15% amounts are $545,500, $306,850, $613,700, and $579,600, respectively. Taxable income above the applicable maximum 15% amount generally enters the 20% band for gains subject to the standard maximum capital-gains rates. [3]

These are taxable-income thresholds, not conversion limits and not amounts a household is instructed to realize. They also do not apply identically to collectibles gain, unrecaptured section 1250 gain, or every other special capital-gain category.

Assume a married couple filing jointly has $70,000 of ordinary taxable income and $40,000 of net long-term capital gain in 2026. These amounts are already stated after deductions for purposes of this simplified illustration. The couple has no qualified dividends, special-rate gains, capital-loss carryovers, NIIT, state tax, or other tax interactions.

The example does not mean a conversion always creates an extra 15 cents of capital-gains tax per dollar. If the gain was already entirely in the 15% band, a smaller conversion might not change its regular capital-gains rate. If total taxable income approaches the 20% threshold, the interaction may differ again. If there is no net long-term gain or qualified dividend, there may be no preferential-rate amount to displace.

The Net Investment Income Tax, or NIIT, is a separate 3.8% tax. For individuals, it generally applies to the lesser of net investment income or the amount by which modified adjusted gross income exceeds a filing-status threshold. The statutory thresholds are $200,000 for single and head-of-household filers, $250,000 for married filing jointly and qualifying surviving spouses, and $125,000 for married filing separately. IRS guidance notes that these individual thresholds are not indexed for inflation. [4] [5]

IRS guidance generally excludes distributions from qualified retirement plans and IRAs described in sections 401(a), 403(a), 403(b), 408, 408A, and 457(b) from net investment income. That means the Roth conversion amount is not automatically itself subject to the 3.8% NIIT. But a taxable retirement distribution can increase AGI and therefore the MAGI side of the NIIT calculation. When the household already has net investment income, a conversion may increase the smaller amount on which NIIT is computed. [4] [5]

Capital gains are not always known when a Roth conversion is planned. Mutual funds may distribute gains late in the year. A business or investment property sale may close unexpectedly. Tax-loss harvesting may change the net result. A retiree may sell appreciated assets to fund living expenses or the tax payment itself.

A conversion completed before those figures are known can leave less flexibility. Post-2017 Roth conversions generally cannot be recharacterized back to a Traditional IRA simply because the final tax result is higher than expected. That makes updated year-to-date information and more than one scenario worth reviewing before instructions are final. [1]

1. Separate realized gains from unrealized appreciation; only completed taxable transactions generally enter the current return.
2. Classify expected gains as short-term, long-term, collectible, unrecaptured section 1250, or another applicable category.
3. Include expected qualified dividends and year-end fund distributions.
4. Account for current-year capital losses and available carryovers.
5. Update ordinary income for wages, pensions, RMDs, interest, taxable Social Security, and other distributions.
6. Estimate the taxable conversion amount after valid IRA basis and aggregation rules.
7. Compare no-conversion and multiple partial-conversion amounts using the same gain assumptions.
8. Test whether any scenario crosses a capital-gains or NIIT threshold.
9. Review state income-tax treatment separately.
10. Revisit withholding and estimated payments after the projection changes.

For conversion payment timing, read When Are Roth Conversion Taxes Due? For the taxable conversion amount, review How Are Roth Conversions Taxed?.

These questions do not determine whether either transaction is appropriate. They help identify the inputs a qualified tax or financial professional may need for a complete comparison.

1. How much ordinary taxable income is expected before any conversion?
2. How much of the proposed conversion is expected to be taxable?
3. Which gains are already realized, and which are only possible?
4. Are the gains short-term, long-term, or subject to a special rate?
5. How much qualified-dividend income is expected?
6. Are capital-loss carryovers or current losses available?
7. Which 2026 capital-gains band contains each portion of the net gain?
8. Could MAGI cross an NIIT threshold?
9. Could the same income affect Medicare IRMAA, Social Security taxation, Marketplace credits, or other income-linked rules?
10. Would selling assets to pay the conversion tax create an additional gain?
11. What changes if the conversion is smaller, delayed, or spread across more than one tax year?
12. Has the projection been updated close enough to the transaction date to include known year-end income?

• A taxable Roth conversion is generally ordinary income, not a capital gain.
• Ordinary income can reduce the taxable-income space available in the 0% or 15% long-term capital-gains band.
• The 2026 capital-gains thresholds apply to taxable income, not gross conversion proceeds or account value.
• The conversion itself is generally excluded from net investment income, but its taxable amount may increase MAGI used for NIIT.
• Qualified dividends, losses, deductions, IRA basis, special-rate gains, and state tax can materially change the result.
• Selling appreciated assets to pay conversion tax may add another gain to the same-year projection.
• The useful comparison is total projected tax across scenarios—not the conversion’s ordinary bracket in isolation.