Backdoor Roth IRA Calculator

About the Backdoor Roth IRA Calculator

The Backdoor Roth IRA Calculator is for savers who cannot make a full direct Roth IRA contribution and want to estimate the tax cost of contributing to a traditional IRA and then converting to Roth. For 2026, the standard IRA contribution limit is $7,500, with an $1,100 catch-up for age 50 or older. Full direct Roth contributions phase out above modified AGI of $153,000 for single filers and $242,000 for married filing jointly in 2026.

The main complication is the pro-rata rule. If you hold pre-tax money in any Traditional, SEP, or SIMPLE IRA on December 31 of the conversion year, the IRS treats the conversion as coming partly from pre-tax and partly from after-tax dollars. That means even a nondeductible contribution can trigger a taxable conversion.

Enter your intended contribution, existing IRA balances, and marginal tax rate to see how much of the conversion is tax-free, how much is taxable, and how much the pro-rata rule changes the strategy.

When This Page Helps

A backdoor Roth is straightforward only when your pre-tax IRA balance is zero. This page shows how much tax the pro-rata rule creates when you still hold Traditional, SEP, or SIMPLE IRA money, which helps you decide whether to convert now, wait, or first move pre-tax IRA assets into an employer plan.

How to Use the Inputs

1. Enter the nondeductible traditional IRA contribution amount you plan to convert.
2. Enter your existing Traditional IRA pre-tax balance (if any).
3. Enter any SEP or SIMPLE IRA balances (these count for pro-rata).
4. Enter your marginal tax rate.
5. Review the pro-rata calculation and tax cost of the conversion.
6. Use the scenario table to see how pre-tax balances change the result.

Example Calculation

Tips & Best Practices

• The cleanest backdoor Roth happens when your year-end pre-tax IRA balance is zero.
• Roll pre-tax Traditional IRA money into your 401(k) before year-end to eliminate the pro-rata issue.
• The pro-rata rule considers ALL Traditional, SEP, and SIMPLE IRA balances — not just the account you convert from.
• Pro-rata is calculated as of December 31 of the conversion year — timing matters.
• For 2026, the standard IRA contribution limit is $7,500 and the age-50+ catch-up raises it to $8,600.
• Keep records of Form 8606 filing for nondeductible contributions because they track your basis.

When the strategy is clean

The clean version is simple: no pre-tax Traditional, SEP, or SIMPLE IRA balance at year-end, a nondeductible contribution, then a prompt conversion. Using the 2026 standard limit of $7,500, a fully tax-free conversion growing at 7% for 30 years would reach roughly $57,000.

When the pro-rata rule gets expensive

If you still hold $100,000 of pre-tax IRA money and add a $7,500 nondeductible contribution, only about 7.0% of a $7,500 conversion is tax-free. Roughly $523 would convert tax-free and roughly $6,977 would be taxable. That is why many high earners first roll pre-tax IRA money into a 401(k) or other eligible employer plan if the plan accepts roll-ins.

Repeating the strategy annually

Some savers use the backdoor Roth every year. Contributing and converting $7,500 annually for 20 years at 7% would build roughly $329,000 of Roth assets, assuming the strategy stays available and pre-tax IRA balances do not trigger pro-rata tax in later years.

Frequently Asked Questions

• What is the backdoor Roth IRA strategy?

  It is a two-step strategy used by some higher-income savers: make a nondeductible contribution to a traditional IRA and then convert that amount to a Roth IRA. The mechanics are simple when there are no pre-tax Traditional, SEP, or SIMPLE IRA balances at year-end.

• What is the pro-rata rule?

  The IRS treats all of your Traditional, SEP, and SIMPLE IRA balances as one combined pool when you convert. That means the tax-free and taxable pieces of the conversion are determined across the entire pool, not just the account you convert from.

• How do I avoid the pro-rata rule?

  The cleanest workaround is often to move pre-tax IRA money into an employer plan that accepts roll-ins before the end of the conversion year. Employer-plan balances are generally not counted in the IRA pro-rata calculation.

• Is the backdoor Roth IRA legal?

  Current IRS rules allow nondeductible traditional IRA contributions and Roth conversions, which is what the backdoor Roth strategy relies on. The tax result still depends on the pro-rata rule, proper Form 8606 reporting, and any future law changes.

• Should I convert immediately after contributing?

  Many savers convert soon after making the nondeductible contribution so there is less time for gains to accumulate in the traditional IRA before conversion. Gains that build up before the conversion can create a small additional taxable amount.

• What forms do I file for a backdoor Roth?

  Form 8606 is the core reporting form for nondeductible IRA contributions and Roth conversions. Your brokerage will also issue Form 1099-R reporting the conversion distribution.