Backdoor Roth IRA Calculator
High-income earners who exceed the Roth IRA direct contribution income limits can still fund a Roth IRA through a strategy commonly called the backdoor Roth: make a non-deductible contribution to a traditional IRA (which has no income limit) and then convert the traditional IRA balance to Roth. The tax on the conversion depends on whether you hold any other pre-tax traditional IRA funds at the time of conversion. If you have no other traditional, SEP, or SIMPLE IRA funds, the conversion of a purely non-deductible traditional IRA contribution results in no additional tax because the basis (the amount already taxed) equals the amount converted. However, if you hold any pre-tax IRA balances, the pro-rata rule applies: the taxable portion of any conversion is prorated across all traditional IRA funds, meaning you cannot selectively convert only the after-tax funds. For 2025, the Roth IRA direct contribution limit phases out between $150,000 and $165,000 of MAGI for single filers, and between $236,000 and $246,000 for married filing jointly. This calculator identifies whether you exceed those thresholds, applies the pro-rata rule to determine the taxable portion of a conversion, estimates the tax cost, and projects the long-term value of tax-free growth in the Roth versus keeping the funds in a taxable account.
At age --, MAGI --, --, with -- in pre-tax IRAs, your backdoor Roth contribution of -- will incur -- in federal tax on conversion. Projected Roth balance at retirement: --.
How the backdoor Roth conversion is calculated
A backdoor Roth starts with a non-deductible Traditional IRA contribution (up to the annual limit) and immediately converts it to a Roth IRA. The pro-rata rule determines how much of the conversion is taxable. If you have other pre-tax IRA balances, a portion of the conversion becomes taxable income.
contribution limit = 7,000 (under 50) or 8,000 (age 50+)
total IRA balance = pre-tax IRAs + after-tax IRAs
pre-tax percentage = pre-tax IRAs / total IRA balance
taxable portion = contribution limit x pre-tax percentage
non-taxable portion = contribution limit x (1 - pre-tax percentage)
conversion tax = taxable portion x (marginal rate / 100)
future value = (contribution limit + after-tax IRAs + pre-tax IRAs) x (1 + return)^years
Worked example: clean backdoor
Age 45, single, MAGI $200,000, $7,000 contribution, zero pre-tax IRAs, 7% return, 25 years, 22% tax rate:
- Contribution limit = $7,000 (age under 50)
- Total IRA balance = 0 + 0 = $0 (clean backdoor)
- Pre-tax percentage = 0 / (7,000 + 0) = 0%
- Taxable portion = 7,000 x 0 = $0 (no pre-tax IRAs)
- Conversion tax = 0 x 0.22 = $0 tax owed
- Future value = 7,000 x (1.07)^25 = $38,188.48
Worked example: pro-rata rule applies
Same scenario but with $50,000 in existing Traditional IRA (pre-tax):
- Contribution limit = $7,000
- Total IRA balance = 50,000 + 0 = $50,000 (not clean)
- Pre-tax percentage = 50,000 / 57,000 = 87.7%
- Taxable portion = 7,000 x 0.877 = $6,139
- Conversion tax = 6,139 x 0.22 = $1,350.58 tax owed
- After conversion and growth, $7,000 in Roth grows to $38,188.48
Important considerations and risks
The backdoor Roth is legal and widely used, but execution is critical. The IRS expects the conversion to happen within a few days of the initial contribution. Waiting months or longer may trigger scrutiny. Additionally, if you receive a large distribution from a 401(k) or employer plan to an IRA in the same year as your backdoor conversion, the pro-rata rule will apply to both, potentially triggering a large unexpected tax bill.
If you have significant pre-tax IRA balances, the pro-rata rule can make a backdoor Roth inefficient. For example, if you have $500,000 in Traditional IRAs and want to convert $7,000, roughly 86% of the conversion becomes taxable. In such cases, consider whether the tax cost outweighs the benefit of tax-free growth in the Roth.
The conversion itself is reported on Form 8606, which must be filed with your tax return. If you fail to file Form 8606, the IRS may treat the entire distribution as taxable income. Additionally, if you ever need to withdraw the money before age 59.5, you may face a 10% early withdrawal penalty (with limited exceptions such as disability or first-time home purchase, but conversions have a five-year rule). Consult a tax professional before executing a backdoor Roth, especially if you have complicated IRA balances or other income situations.
Backdoor Roth IRA: frequently asked questions
What is a backdoor Roth IRA and why do it?
A backdoor Roth IRA is a two-step process for high earners who exceed the Roth IRA direct contribution income limits. First, you contribute non-deductible dollars to a Traditional IRA (no income limit exists). Second, you immediately convert the Traditional IRA to a Roth IRA (no income limit on conversions). The result is money inside a Roth that grows tax-free, even though your MAGI disqualifies you from direct Roth contributions.
Who can do a backdoor Roth IRA?
Technically, anyone can make a non-deductible Traditional IRA contribution and convert it to a Roth. However, the strategy is primarily useful for single filers with MAGI above $150,000 or married couples with MAGI above $236,000, because those are the Roth direct contribution phase-out ranges. If your MAGI is below those thresholds, you may contribute directly to a Roth and avoid the extra steps.
What is the pro-rata rule and why does it matter?
The pro-rata rule (IRC Section 408(d)(2)) requires that if you have pre-tax Traditional IRA funds (such as rolled-over 401(k) money or previous deductible IRA contributions), a portion of your conversion will be taxable. Specifically, the tax is calculated as: taxable portion = conversion amount times (pre-tax IRA balance divided by total IRA balance). If you have 50,000 in pre-tax IRAs and convert 10,000, you owe tax on roughly half the conversion.
What is a clean backdoor Roth IRA?
A clean backdoor Roth is when you have zero pre-tax IRA balances at the time of conversion. No pro-rata rule applies, no tax is owed, and the entire contribution ends up inside the Roth completely tax-free. This is the simplest case and the goal most people aim for when executing a backdoor Roth.
How do I actually execute a backdoor Roth IRA?
Step 1: Open a Traditional IRA if you do not have one. Step 2: Contribute the maximum amount (7,000 for 2025 if under age 50, or 8,000 if age 50 or older). You are using after-tax dollars, so this is NOT tax-deductible. Step 3: Wait a few business days for the contribution to settle. Step 4: Immediately (same day or next business day) convert the Traditional IRA to a Roth IRA at the same institution. File Form 8606 with your tax return to report the conversion. If you have other pre-tax IRAs, consult a tax professional.
What happens to the money after conversion?
Once inside a Roth IRA, the money grows tax-free. You do not owe tax on growth, dividends or capital gains inside the Roth. You cannot withdraw contributions before age 59.5 without penalty (with limited exceptions), but the tax-free growth is permanent. Roth IRAs also do not have required minimum distributions (RMDs), which means your money can keep growing indefinitely if you do not need it.
Official sources
- IRS Publication 590-A (Contributions to Individual Retirement Arrangements): irs.gov/publications/p590a.
- IRS Publication 590-B (Distributions from Individual Retirement Arrangements): irs.gov/publications/p590b.
- IRS Form 8606 (Nonqualified IRAs): irs.gov/pub/irs-pdf/f8606.pdf.
- IRS Rev. Proc. 2024-40 (2025 tax year items): irs.gov/pub/irs-drop/rp-24-40.pdf.
Reviewed by the CalculatorHub team, edited by James Graham, 13 June 2026. See our methodology. General information, not financial or tax advice.