Taxable Conversion Amount
$60,000
Retirement
Roth Conversion Calculator
Estimate the tax cost of converting a Traditional IRA to a Roth IRA, compare single-year vs. multi-year spread conversions, and see exactly how the IRS pro-rata rule applies to your money.
Federal tax:$13,618/18.2% effective
Conversion Worksheet
Filing Status
Tax Year
Traditional IRA Total Balance$150,000
Other Income$80,000
Optional state tax rate0%
Optional annual IRMAA surcharge$0
Pre-Tax Amount$120,000
After-Tax Basis (Nondeductible)$30,000
Conversion Amount$75,000
Converting 50% of total Traditional IRA balance
Pro-Rata Balance Split
Pre-Tax Portion
$120,000 (80%)
After-Tax Basis
$30,000 (20%)
Conversion Breakdown ($75,000)
Under the IRS pro-rata rule, you cannot choose to convert only after-tax dollars. Your conversion is composed of:
Taxable: $60,000Tax-Free Basis: $15,000
Conversion Estimate
Federal tax estimate: $13,618
Converting $75,000 results in $60,000 taxable income (80% pro-rata), with an estimated tax of $13,618 at 24% marginal rate.
Tax liability is an incremental federal income-tax estimate attributable to this conversion. It is not payroll withholding, a final Form 1040 tax calculation, or a guaranteed amount due.
24% marginal bracket
Effective Tax Rate
18.2%
Remaining After-Tax Basis
$15,000
Post-Conversion Traditional Balance
$75,000
Estimated combined tax
$13,618
Includes $0 estimated state tax and $0 IRMAA input.
Total Income: $140,000 · Taxable Income: $124,250 (after 15,750 standard deduction)
Isolated tax calculation: Tax on $124,250 total income minus tax on $64,250 other income alone.
2025 Bracket Breakdown
How your conversion is taxed across brackets
| Rate | Income Range | Taxable Conversion Allocation |
|---|---|---|
10% | $0 — $11,925 | $11,925 other |
12% | $11,925 — $48,475 | $36,550 other |
22% | $48,475 — $103,350 | +$39,100 converted|$15,775 other |
24% | $103,350 — $197,300 | +$20,900 converted |
32% | $197,300 — $250,525 | Unused |
35% | $250,525 — $626,350 | Unused |
37% | $626,350 — + | Unused |
Income is taxed progressively. Your other income fills the lower brackets first, and your taxable Roth conversion is taxed on top of that other income.
Other Income
Conversion Portion
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Disclosure
Estimate only; not tax, legal, or investment advice. Consult a CPA or CFP before executing a Roth conversion. This calculator uses federal tax brackets only. It does not include state taxes, NIIT, IRMAA, RMDs, Social Security thresholds, the 5-year Roth rule, or early withdrawal penalties. Brackets follow the official IRS tables: the One Big Beautiful Bill Act (P.L. 119-21) made the 10/12/22/24/32/35/37% rates permanent, and 2026 amounts are from Rev. Proc. 2025-32.
About this calculator
Method, formulas, and limits.What this does
Estimates the federal tax cost of converting Traditional IRA money to a Roth IRA, applies the IRS pro-rata rule to separate pre-tax from after-tax basis, and compares a single-year conversion against spreading the same conversion across multiple tax years.
Who it is for
Retirement savers considering a backdoor or standard Roth conversion, financial planners running what-if tax scenarios, and taxpayers who want to see which marginal bracket their conversion lands in before they commit.
How it works
Enter your Traditional IRA total balance, your pre-tax amount and after-tax basis, your other taxable income, and a conversion amount. The calculator applies the pro-rata rule, computes taxable and tax-free portions of the conversion, runs the federal bracket math for 2024-2026, and shows both single-year and multi-year tax totals with a visual bracket breakdown.
Limitations
Estimates federal income tax only and ignores state taxes, NIIT, IRMAA, AMT, deductions beyond the standard deduction, and future tax-law changes. Assumes constant tax brackets across spread years and a constant other-income level.
Key calculations
- Pro-Rata Taxable Amount
- taxableAmount = conversionAmount × (preTaxAmount / totalBalance). Only the pre-tax share of your Traditional IRA is taxable when converted.
- Federal Tax Liability
- Tax is computed progressively across 2024-2026 federal brackets using your other income plus the taxable conversion amount.
- Multi-Year Spread
- Spreading the conversion over N years divides the conversion into annual chunks. Each year's tax is computed independently against your other income.
Reference ranges
- Typical Conversion Scenarios
- A $50,000 conversion for a single filer with $80,000 other income typically lands in the 22-24% bracket. Spreading over 2-3 years can keep each year below a bracket threshold.
- Pro-Rata Rule Impact
- If 80% of your Traditional IRA is pre-tax, then 80% of every conversion dollar is taxable regardless of which dollars you intend to convert.
- Multi-Year Savings
- Spreading a large conversion over 3-5 years often reduces total tax by 5-15% when it avoids pushing income into a higher bracket in any single year.
How to use it
- 1.Enter your IRA balancesType your Traditional IRA total balance, pre-tax amount, and after-tax basis. The pro-rata bar updates live to show the split.
- 2.Set your income and conversionEnter your other taxable income and the amount you plan to convert. The calculator shows the marginal bracket and estimated tax cost immediately.
- 3.Compare single vs. multi-yearSwitch to Multi-Year Spread to see the tax comparison chart and per-year projection table for spreading the conversion.
The IRS pro-rata rule says you cannot convert only the after-tax basis in your Traditional IRA. Every conversion is proportionally split between pre-tax and after-tax money based on your total IRA balance, so the taxable share equals conversionAmount × (preTaxAmount / totalBalance).
Often yes. Converting a large amount in one year can push you into a higher marginal bracket. Spreading the same total over several years keeps each year's taxable income lower, which frequently reduces the total tax paid.
No. It estimates federal income tax only. State taxes, NIIT, IRMAA, AMT, and other surtaxes are not included, so your actual tax bill may differ.
After-tax basis is the money in your Traditional IRA that was already taxed (nondeductible contributions or converted after-tax dollars). It is tracked on IRS Form 8606 and is not taxed again when converted to a Roth IRA.
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