Separate the tax cost from the investment comparison
The first result estimates the increase in regular federal income tax if the specified amount is added to your ordinary taxable income in 2026. The second compares the future value of that amount in a converted account with its future value in a traditional account after the tax rate you enter.
This is a simplified comparison of two endpoints. “Keep traditional” means leaving the amount invested and applying your chosen effective tax rate to the entire future withdrawal at the comparison date. It does not forecast future tax brackets or model a series of conversions.
Worked example: crossing a bracket
A single filer with $50,000 of ordinary taxable income and a $20,000 fully taxable conversion has $400 of room below the 2026 $50,400 threshold. In this simplified calculation, $400 is taxed at 12% and the remaining $19,600 at 22%: $48 + $4,312 = $4,360 of additional federal income tax. That is an average 21.8% of the conversion, before other tax effects.
How the tax payment changes the comparison
If the tax is paid from outside money, the full conversion amount stays invested. To compare equal starting resources, the calculation subtracts what that outside tax payment could have grown to at your assumed after-tax outside return.
If tax is withheld from the distribution, the converted amount is reduced by the estimated tax. The tool assumes that reduced amount is the only amount entering the Roth account. It does not calculate penalties or determine whether the distribution and subsequent withdrawal meet the applicable tax rules.
What a break-even result means
Outside tax payment: net difference = C × g × f − T × h
Withheld tax: net difference = (C × f − T) × g
g = account growth factor
h = outside-money growth factor
f = assumed future withdrawal tax rate
The break-even future tax rate is the rate that makes the net difference zero at the chosen year. For outside tax payments it is (T ÷ C) × (h ÷ g). For withheld taxes it is T ÷ C. If that threshold is above 100%, no rate in the accepted 0–100% range makes conversion favorable under these assumptions.
A break-even year exists only if the growth and tax assumptions create a crossing at or after year zero. When both growth rates are equal, or the tax is withheld, more years do not reverse which scenario leads. This is why a universal “conversion pays for itself in X years” answer would be misleading.
For conversion timing, read the Roth conversion ladder guide and the two distinct five-year rules. Neither timing guide determines that a conversion is beneficial for you.
2026 ordinary income tax brackets
Thresholds below are upper limits for each rate, applied progressively to taxable income after deductions. Source: IRS Revenue Procedure 2025-32, section 4.01, tables 1–4; reviewed October 25, 2026.
| Rate | Single | Married filing jointly | Head of household | Married filing separately |
|---|---|---|---|---|
| 10% | $12,400 | $24,800 | $17,700 | $12,400 |
| 12% | $50,400 | $100,800 | $67,450 | $50,400 |
| 22% | $105,700 | $211,400 | $105,700 | $105,700 |
| 24% | $201,775 | $403,550 | $201,750 | $201,775 |
| 32% | $256,225 | $512,450 | $256,200 | $256,225 |
| 35% | $640,600 | $768,700 | $640,600 | $384,350 |
| 37% | No upper limit | No upper limit | No upper limit | No upper limit |
Know when this tool is too simple
This tool assumes no after-tax basis and does not model tax credits, changing deductions, capital gains interactions, alternative minimum tax, surtaxes, state income tax, benefit or premium changes, distribution penalties, or required distributions. It also assumes a future Roth withdrawal with no additional tax; that is a model condition, not a determination that you qualify.
Use the result to prepare questions for a qualified tax professional. Check actual account and tax records before making a conversion or distribution.
Questions about this calculation
Is my whole conversion taxed at the highest bracket?
This model calculates tax on ordinary taxable income before and after the conversion, then takes the difference. A conversion crossing a bracket boundary is split across those brackets. The result is not simply the entire conversion multiplied by the top rate.
Should I enter gross income or taxable income?
Enter ordinary taxable income after deductions, before the conversion. Do not enter gross pay or account balance in that field. This simplified tool does not calculate deductions or the effects of capital gains and credits.
Why is there sometimes no break-even year?
When account growth and outside-money growth are equal, time cancels from this comparison. The result depends on the tax rates. Different growth assumptions can produce a crossing; this calculator only reports one if the algebra produces a nonnegative year.
Can I use this for a conversion containing after-tax basis?
No. This calculation assumes the entire amount is taxable. It does not model after-tax basis, aggregation or allocation rules. Review your actual circumstances with a qualified tax professional.
Official sources and review date
- IRS Revenue Procedure 2025-32 (PDF), section 4.01, tables 1–4: ordinary federal tax brackets for tax year 2026. Reviewed October 25, 2026.
- IRS Roth IRAs overview: consult official guidance on Roth account rules and distributions. Referenced October 25, 2026; this calculator does not determine eligibility or qualified distribution status.
- RetireCalc methodology: model assumptions and derivation, October 25, 2026.