Backdoor Roth Calculator

2026 rules

Check whether your backdoor Roth will be tax-free, or how much of it the pro-rata rule makes taxable.

Your numbers

Nondeductible IRA contribution

Pre-tax IRA balances on Dec 31 (traditional, SEP, SIMPLE)

Money in a 401(k) does not count.

Growth before you convert

Your marginal tax rate

Result

Tax on the backdoor conversion$0

Converted to Roth$7,500
Tax-free share (basis ÷ all IRA money)100%
Taxable part$0
Tax at your rate$0
Basis left in traditional IRAs$0

With no other pre-tax IRA money, only the growth before you convert is taxable.

How it works

A backdoor Roth is a nondeductible traditional IRA contribution converted to a Roth. If that's your only IRA money, only the growth before you convert is taxable.

If you have other pre-tax money in traditional, SEP or SIMPLE IRAs on December 31, the IRS treats all of it as one pot. The tax-free share of your conversion is your basis divided by the total.

2026 figures: IRS Rev. Proc. 2025-32 (2026 inflation adjustments); IRS Notice 2025-67 (2026 retirement plan limits); CMS 2026 Medicare Parts A & B premiums and deductibles.

Questions

How do I avoid the pro-rata rule?

Roll pre-tax IRA money into your current employer's 401(k) before December 31 of the year you convert, if the plan accepts roll-ins. 401(k) balances don't count.

Which form do I file?

Form 8606, which records the nondeductible contribution and works out the taxable part of the conversion.