Basis topic
See how the pro-rata rule can make a Roth conversion partly taxable even when after-tax basis exists.
The prefilled calculator example uses $40,000 of basis and $200,000 of traditional IRA balance to demonstrate how basis can affect a taxable conversion estimate.
The pro-rata rule is especially important when an IRA contains both pre-tax and after-tax amounts.
The calculator simplifies this by using basis divided by traditional IRA balance to estimate the excluded portion of a conversion.
Because aggregation and reporting rules can be nuanced, the page is intended for educational modeling rather than filing guidance.
Open the calculator with basis and IRA balance example assumptions prefilled, then replace them with verified records before relying on the output.
Open the calculatorThis educational page explains pro-rata assumptions only and does not provide tax, financial, legal, or investment advice.
This Roth Conversion Calculator is for educational and illustrative purposes only. It does NOT constitute tax, financial, legal, or investment advice. The calculation results are based on the information you provide and the latest IRS tax rules, which are subject to change. We do not guarantee the accuracy of the results. Please consult a licensed Certified Public Accountant (CPA), financial advisor, or tax professional before making any financial decisions.