Roth Rollover Calculator
Roth rollover calculator works out Taxable portion of the conversion and Tax-free portion (return of basis) from Tax year of the conversion, Filing status and Amount to convert. The default figures on this page give total tax cost of converting of 23,164.00; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
7 steps
- A pre-tax employer plan rolled into a Roth IRA is taxable in full.
- Taxable income without the conversion = 80000 - 16100 (2026 standard deduction) = 63900, tax 8770.
- Taxable income with it = 163900, tax 31934.
- Federal tax the conversion adds = 31934 - 8770 = 23164.
- The conversion pushes you from the 22% bracket into the 24% bracket, so part of it is taxed at each rate in between.
- In 20 years at 7% the Roth holds 386968.45, all of it yours if the distribution is qualified.
- Left pre-tax, the same 100000 grows to 386968.45 and is taxed at 22% on the taxable share, leaving 301835.39.
Figures from US federal tax tables (IRS), 2026 rules, checked 31 August 2026. Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed · how reference data is kept current
Sources and references
3 sources
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Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the roth rollover calculator calculates
Works out the taxable portion of a traditional-to-Roth conversion under the IRC 408(d)(2) pro-rata rule, the federal tax it actually adds at your own marginal rates, any state tax and 72(t) additional tax on withheld amounts, and whether converting beats leaving the money pre-tax.
How to use this roth rollover calculator
Enter Tax year of the conversion, Filing status, Amount to convert and Your other ordinary income this year. Taxable portion of the conversion updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Taxable portion of the conversion, Tax-free portion (return of basis) and Taxable fraction under the pro-rata rule.
The method follows 26 U.S.C. 408A(d)(3) - a conversion is treated as a distribution includible in gross income in the year of conversion, and the 10% additional tax does not apply to the converted amount, 26 U.S.C. 408(d)(2) - all individual retirement plans of the taxpayer are treated as one contract and all distributions during the year as one distribution, which is the pro-rata rule and IRS Publication 590-A, Converting From Any Traditional IRA Into a Roth IRA, and IRS Form 8606 instructions, Part II.
What you can compare
Change one input at a time to see how it affects Taxable portion of the conversion, Tax-free portion (return of basis) and Taxable fraction under the pro-rata rule. The inputs you can vary are Tax year of the conversion, Filing status, Amount to convert, Your other ordinary income this year, Itemised deductions and After-tax basis in those IRAs (Form 8606).
Understanding Taxable portion of the conversion, Tax-free portion (return of basis) and Taxable fraction under the pro-rata rule
An estimate from published federal rate tables. It does not model AMT, IRMAA Medicare surcharges, net investment income tax, the taxation of Social Security benefits, credit phase-outs or state rules beyond one flat rate - all of which a large conversion can trigger. Confirm with a tax adviser before converting.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
Is a Roth rollover worth it?
Works out the taxable portion of a traditional-to-Roth conversion under the IRC 408(d)(2) pro-rata rule, the federal tax it actually adds at your own marginal rates. On the figures this page opens with — amount to convert 50,000 USD, your other ordinary income this year 80,000 USD and after-tax basis in those IRAs (Form 8606) 0 USD — the total tax cost of converting is 23,164. Put your own figures in their place and the working updates beside the result.
What is the biggest Roth conversion mistake?
On the figures this page opens with — amount to convert 50,000 USD, your other ordinary income this year 80,000 USD, after-tax basis in those IRAs (Form 8606) 0 USD and your age 45 — the total tax cost of converting is 23,164. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the roth rollover calculator?
You need Tax year of the conversion, Filing status, Amount to convert, Your other ordinary income this year, Itemised deductions, After-tax basis in those IRAs (Form 8606), Your age and State income tax rate on the conversion. The page opens with default figures that give total tax cost of converting of 23,164.00, so you can see the scale before entering your own.
What does this roth rollover calculator show?
It shows Taxable portion of the conversion, Tax-free portion (return of basis), Taxable fraction under the pro-rata rule, Federal tax the conversion adds, State tax on the conversion, 10% additional tax on amounts withheld, not converted, Total tax cost of converting and Effective tax rate on the conversion, with the working and any warnings for your entries.
Can I check how the roth rollover calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.