Calculate your exact tax liability using the IRS pro-rata rule — in seconds.
Step 1 — Non-Deductible Contribution: You contribute after-tax dollars to a traditional IRA. Because you exceed the income limit for a deductible contribution, you file Form 8606 to track your basis.
Step 2 — Roth Conversion: You convert the traditional IRA to Roth. Normally this is tax-free since you already paid tax. But…
The Pro-Rata Rule (The Catch): The IRS treats ALL your traditional IRA money as one pool. The taxable portion of your conversion is calculated as:
If you have $0 in other pre-tax IRAs: Your conversion is 100% tax-free — the ideal backdoor Roth scenario.
If you have pre-tax IRA money: A portion of your conversion becomes taxable income. Many people do a rollover to a 401(k) first to eliminate this problem.
Enter your non-deductible IRA contribution amount, the total balance across all your traditional/SEP/SIMPLE IRAs, your total non-deductible basis from past Form 8606 filings, and the amount you plan to convert. Then add your ordinary income and filing status so the calculator can estimate your actual tax bracket impact.
The results show your taxable conversion amount, the pro-rata percentage, estimated additional taxes owed, and whether the backdoor Roth makes sense given your full IRA picture.
The Backdoor Roth IRA is one of the most powerful tax strategies available to high earners — but it's also one of the most misunderstood. In 2025, the Roth IRA income limit phases out starting at $150,000 for single filers and $236,000 for married couples filing jointly. If you're above those thresholds, the backdoor strategy is often your only path to tax-free growth.
Here's the problem most people miss: if you have any pre-tax money sitting in a traditional IRA — say, $100,000 from a rollover — and you try to convert just $7,000, the IRS won't let you cherry-pick. The pro-rata rule forces you to treat 93.5% of that conversion as taxable. On a $7,000 conversion, that's $6,545 added to your income, potentially costing $1,600–$2,600 in extra taxes at typical brackets.
Conversely, if you have zero pre-tax IRA funds, the conversion is entirely tax-free — which is why many advisors recommend rolling existing pre-tax IRA balances into a workplace 401(k) before doing the backdoor conversion. This calculator helps you model both scenarios so you can make the right call.
The IRS uses the pro-rata rule (sometimes called the "cream in the coffee" rule) to determine what portion of your conversion is taxable. Here's the exact formula:
The marginal tax rate is estimated using 2024/2025 IRS tax brackets based on your filing status and total income (ordinary income + taxable conversion amount). The calculator uses real bracket thresholds for accurate estimates.
You're in the ideal scenario. With no pre-tax IRA balance, the pro-rata rule results in 100% of your conversion being tax-free. You contributed after-tax dollars and you're converting those same after-tax dollars — no taxable income is created. This is why many high earners keep their traditional IRA balance at zero.
No — 401(k), 403(b), and 457(b) balances are NOT included in the pro-rata rule. Only traditional IRA, SEP-IRA, and SIMPLE IRA accounts count. This is why rolling pre-tax IRA funds into a 401(k) (if your plan allows it) can clear the deck for a clean backdoor Roth conversion.
Yes, and it's highly recommended if you're both eligible. Each spouse has their own IRA and their own contribution limit. However, the pro-rata rule is calculated separately for each spouse based on their individual IRA balances — your spouse's pre-tax IRA does not affect your calculation.
Yes, as of the time of writing. Congress has discussed eliminating it (notably in the 2021 Build Back Better proposal), but it remains legal. The IRS itself has acknowledged the strategy. That said, it's worth consulting a tax professional if your situation is complex, particularly if you have large existing IRA balances.