CALCULATOR
Backdoor Roth IRA Pro Rata Calculator
The backdoor Roth seems simple. Contribute, convert, done. But if you have other pre-tax IRA money, the IRS pro rata rule taxes part of every conversion. Find out exactly how much before you file.
Not tax advice. Consult a CPA before executing a Roth conversion.
Your IRA Balances
Include all traditional, SEP, and SIMPLE IRA balances. The IRS pools them all together.
Sum of all traditional, SEP, SIMPLE IRAs
From your prior Form 8606, line 14 (or $0 if first time)
Max $7,000 ($8,000 if age 50+)
How much you plan to convert to Roth this year
How the Pro Rata Rule Works
The IRS treats all your IRAs as one combined account. When you convert money to Roth, the taxable percentage equals the ratio of pre-tax money to total IRA money across every account you own.
Example: You have $93,000 in a pre-tax IRA and contribute $7,000 non-deductible. Your pool is $100,000. Your after-tax ratio is 7%. Convert that $7,000 and only $490 is tax-free. The other $6,510 is taxable income.
Track your after-tax basis on Form 8606 every year — even if no conversion happened. If you lose that record, you'll pay taxes on money you already paid taxes on.
RELATED READING
The Backdoor Roth IRA Pro Rata Rule: What It Is and How to Calculate It
Why the pro rata rule catches high earners off guard, and how to avoid the tax hit.