Taxes · Calculator

Backdoor Roth pro-rata.
How much of your conversion is taxable.

If you have existing pre-tax IRAIndividual Retirement Account (IRA)A retirement account with tax advantages and eligibility rules. Traditional IRA contributions may be deductible; taxable withdrawals generally enter income. Roth contributions use after-tax money, and qualified Roth withdrawals are tax-free.Full definition funds, your backdoor Roth conversionRoth conversionMoving eligible retirement money into a Roth account. Pre-tax amounts and earnings generally create taxable income; nondeductible basis is treated under the applicable aggregation rules. Conversions can affect tax brackets and income-based costs, and separate withdrawal rules apply.Full definition is partially taxable. The IRS aggregates all your non-Roth IRAs and applies the pro-rata rulepro-rata ruleThe IRA conversion calculation generally aggregates your Traditional, SEP and SIMPLE IRAs, including pre-tax balances and after-tax basis. Employer 401(k) balances are not part of that IRA aggregation. Form 8606 determines the taxable and nontaxable portions.Full definition. This calculator shows exactly how much.

The question it answersHow much of my backdoor Roth conversion will actually be taxed?

Rules: United States. Privacy: runs in your browser. What you enter stays on your device unless you copy a share link, which puts your inputs in the link.

US-only. The pro-rata rule applies under IRS Form 8606 reporting and IRC Section 408(d).

WORKED EXAMPLE

You contribute $7,500 non-deductible to a Traditional IRA. You also have $67,500 in pre-tax IRA funds from prior rollovers. Total IRA balance: $75,000. After-tax portion: 10%. Taxable portion of conversion: 90%. Converting $7,500: $6,750 is taxable. At 22% federal: $1,485 in taxes. You wanted a tax-free conversion. It cost $1,485 instead.

YOUR INPUTS

Include ALL Traditional, SEP, and SIMPLE IRA balances. Roth IRA balances are excluded. The IRS aggregates all non-Roth IRAs for this calculation.

This is your basis on Form 8606: money you contributed after-tax but did not deduct.

YOUR CONVERSION
NON-DEDUCTIBLE RATIO
0%
TAX-FREE
$0
TAXABLE
$0
FEDERAL TAX OWED
$0
STATE TAX OWED
$0
TOTAL TAX COST
$0
Effective rate on conversion: 0%
ANALYSIS
Enter your numbers above.
// FORM 8606 REMINDER. File Form 8606 to track non-deductible IRA contributions and report this conversion. Keep these records permanently. irs.gov Form 8606 ↗

Estimate, not tax or legal advice. It applies the current rules listed in the assumptions to the numbers you enter. Details this tool does not model can change the result.

What this tool assumes
  • Total non-Roth IRA balance = pre-tax balance + after-tax basis. December 31 balance is what counts; Roth IRAs are excluded.
  • nonDeductibleRatio = afterTaxBasis / totalIRABalance. taxableAmount = conversionAmount × (1 - ratio). taxFreeAmount = conversionAmount × ratio.
  • Federal and state taxes apply to the taxable portion only.
  • Solution to pro-rata: roll pre-tax IRA balances into a current employer 401(k) (if the plan accepts incoming rollovers). 401(k) balances are excluded from the IRA pro-rata calculation.
  • This tool does not model NIITNet Investment Income Tax (NIIT)A 3.8% extra federal tax on investment income for higher earners (above $200k single, $250k married).Full definition or interaction with phase-outs. Consult a CPA for complex situations.
HOW THIS IS CALCULATED

This tool runs entirely in your browser: no data is sent to any server. The assumptions and default values behind the result are listed under “What this tool assumes” on this page. Verify the methodology or inspect the source code in your browser's dev tools.

Where to go from here

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Backdoor Roth How-To

If your income exceeds the Roth IRA limit, you can still contribute via the backdoor Roth.

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  • Backdoor Roth at FidelitySix steps. Fifteen minutes. Contribute non-deductible to Traditional IRA, convert to Roth, file Form 8606.
  • Mega Backdoor Roth CapacityCalculates remaining mega backdoor Roth room from your salary, 401(k) contribution and employer match.

Calculators are educational estimates, not financial advice. Disclosures · How pages are reviewed