Roth Conversion Calculator 2026
The tax cost of converting a traditional IRA to a Roth in 2026 — which brackets the conversion fills, federal and state tax, the Roth vs stay-traditional outcome after growth, break-even retirement tax rate and a bracket-fill suggestion.
| Brackets the conversion fills | — |
|---|---|
| Effective rate on the conversion | — |
| Room left in the current bracket | — |
| Roth value at withdrawal (tax-free) | — |
| If left traditional: value after tax at retirement | — |
| …plus the conversion tax kept and invested | — |
| Net advantage of converting | — |
| Break-even retirement tax rate | — |
| Penalty check | — |
In short
A Roth conversion adds the converted amount to your taxable income in the year of conversion, taxed at ordinary rates on top of your other income. It pays off when your tax rate now is lower than in retirement, when the tax can be paid from outside money, and when the money has years to grow tax-free; the usual tactic is to convert just enough each year to fill your current bracket, especially in low-income years before RMDs and Social Security.
Who this is for: US savers with traditional IRA or 401(k) balances considering a conversion in a low-income year.
When a Roth conversion makes sense
- Low-income years: after retiring but before Social Security and RMDs, many people sit in the 10–12% bracket — converting up to the top of the 12% or 22% bracket each year turns future 22–24% withdrawals into tax-free ones.
- Fill, don't spill: convert the amount that brings you to the top of your current bracket; the room line shows it.
- Pay from outside: paying the tax from the IRA shrinks the Roth and, under 59½, triggers a 10% penalty on the amount withheld.
- Knock-on effects: higher MAGI can raise Medicare premiums (IRMAA) two years later, make more Social Security taxable, and reduce ACA subsidies.
- Estate planning: heirs inherit a Roth tax-free and must empty it within 10 years, versus taxable withdrawals from a traditional IRA.
- Conversions are irrevocable (no recharacterisation since 2018), and each conversion has its own five-year clock.
See also: Roth vs Traditional IRA Calculator 2026, RMD Calculator 2026 — Required Minimum Distribution.
Assumptions
- Conversion stacked on top of other taxable income and taxed through the 2026 brackets; state tax at the flat rate entered.
- Stay-traditional case: balance grows at the return and is taxed at the retirement rate; tax paid from outside is instead invested at the return less a 20% drag.
- Break-even retirement rate = 1 − Roth value ÷ (traditional value before tax + side account).
Worked example
The conversion fills the rest of the 22% bracket ($45,700) and $4,300 of the 24% bracket: federal tax $11,086 + state $2,500 = $13,586 (27.2% effective). After 15 years the Roth is worth about $119,800 tax-free. Left traditional: $119,800 less 27% = $87,500, plus the $13,586 kept and invested at 4.8% → about $27,500 — total $115,000. Converting is ahead by about $4,900; the break-even federal retirement rate (with 5% state on top) is about 17.9%.
Frequently asked questions
How much should I convert each year?
Enough to fill your current bracket without entering the next — the calculator shows the room left; many retirees convert to the top of the 12% or 22% bracket annually.
Is a Roth conversion taxed as income?
Yes — the converted amount (less any after-tax basis) is added to your ordinary income for the year and taxed at your brackets; there is no 10% penalty on the conversion itself.
Can I convert my 401(k) to a Roth?
Yes — to a Roth IRA (after leaving the employer, or in-service if the plan allows) or in-plan to a Roth 401(k) if offered.
What is the five-year rule for conversions?
Each converted amount must stay in the Roth five years (or until 59½) before it can be withdrawn without the 10% penalty; earnings need five years from your first Roth plus age 59½ to be tax-free.
Is there a deadline or limit for conversions?
Conversions must be completed by 31 December of the tax year (no extension) and there is no dollar or income limit; recharacterisation is no longer allowed.
Will a conversion raise my Medicare premiums?
Possibly — IRMAA surcharges look at MAGI from two years earlier, so a large conversion at 63 or later can raise Part B and D premiums for a year.
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