Backdoor Roth IRA Pro-Rata Tax Calculator
Estimate the tax impact of your Backdoor Roth IRA conversion under the IRS pro-rata rule.
Your non-deductible (post-tax) contributions to your Traditional IRA for the year.
Combined total value of W-2 SEP IRAs, SIMPLE IRAs, and pre-tax Traditional IRAs as of Dec 31. Do NOT include 401(k), 403(b), or Roth IRA balances.
Educational Purpose Disclaimer
This calculator is provided for informational and educational estimation purposes only. All calculations and projections are based on standard mathematical formulas and assumed inputs. The output values should not be considered professional financial, legal, tax, or medical advice. ProCalc is not a registered financial advisor or licensed practitioner. Always consult a qualified professional (such as a Chartered Accountant, certified planner, or physician) before making major decisions.
What is the Backdoor Roth IRA Pro-Rata Tax Calculator?
The Backdoor Roth IRA Pro-Rata Tax Calculator helps high-earning taxpayers determine the tax liability of converting Traditional IRA funds to a Roth IRA. In the US, if your income exceeds the direct Roth IRA contribution limit, the 'Backdoor Roth' strategy is a legal way to fund a Roth IRA. However, if you hold *any* pre-tax money in a Traditional, SEP, or SIMPLE IRA on December 31, the IRS pro-rata rule prevents you from only converting post-tax contributions tax-free. This tool calculates the exact taxable fraction, tax owed, and remaining basis carried forward.
How Does the Backdoor Roth IRA Pro-Rata Tax Calculator Work?
1. Enter Conversion Amount — The total amount you are converting to a Roth IRA this year (usually $7,000, or $8,000 for age 50+).
2. Enter Nondeductible IRA Basis — The portion of your Traditional IRA contribution that was made with post-tax (non-deductible) cash.
3. Input Year-End Pre-Tax Balances — The total combined value of all your pre-tax Traditional, SEP, and SIMPLE IRAs as of December 31.
4. Set Marginal Tax Rate — Enter your combined Federal and State tax bracket.
5. View Taxable Ratio & Tax Owed — Review the breakdown showing your tax-free ratio and estimated tax bill.
Formula & Calculation Method
The IRS Pro-Rata Rule Formula:
Total Combined IRA Value = Pre-Tax IRA Balances + Conversion Amount
Tax-Free Ratio = Nondeductible IRA Basis / Total Combined IRA Value
Tax-Free Conversion Portion = Conversion Amount × Tax-Free Ratio
Taxable Conversion Portion = Conversion Amount - Tax-Free Conversion Portion
Tax Owed:
Tax Owed = Taxable Conversion Portion × Marginal Tax Rate
Remaining Tax Basis:
Remaining Basis = Nondeductible IRA Basis - Tax-Free Conversion Portion (carried forward to next year's IRS Form 8606)
Example Calculation
Example: Backdoor Roth Conversion of $7,000 (all non-deductible), with $21,000 in pre-tax IRAs, at a 32% tax bracket.
- Total Combined IRA Value = $21,000 + $7,000 = $28,000
- Tax-Free Ratio = $7,000 / $28,000 = 0.25 (25% tax-free)
- Tax-Free Portion = $7,000 × 25% = $1,750
- Taxable Portion = $7,000 - $1,750 = $5,250
- Tax Owed on Conversion: $5,250 × 32% = $1,680
- Remaining Basis (Form 8606): $5,250 (carried forward to future conversions)
Frequently Asked Questions
**The IRS Pro-Rata Rule Formula:** Total Combined IRA Value = Pre-Tax IRA Balances + Conversion Amount Tax-Free Ratio = Nondeductible IRA Basis / Total Combined IRA Value Tax-Free Conversion Portion = Conversion Amount × Tax-Free Ratio Taxable Conversion Portion = Conversion Amount - Tax-Free Conversion Portion **Tax Owed:** Tax Owed = Taxable Conversion Portion × Marginal Tax Rate **Remaining Tax Basis:** Remaining Basis = Nondeductible IRA Basis - Tax-Free Conversion Portion (carried forward to next year's IRS Form 8606)
Disclaimer: This financial calculator is provided for educational and estimation purposes only. ProCalc is not a registered financial advisor or SEBI entity. Rates and tax rules may vary.