A Roth conversion moves money from a pre-tax retirement account — a Traditional IRA, SEP IRA, SIMPLE IRA, or a Traditional 401(k) — into a Roth IRA. The converted amount is added to your ordinary income for the year, you pay tax on it at your marginal rate, and from that point forward the entire balance grows tax-free with no required minimum distributions during your lifetime.
The calculator above gives you the upfront tax bill and a projection of how the after-tax balance compounds. Below we explain when a conversion is worth doing, how to minimize the tax cost, and the rules that catch people off guard — particularly the 5-year rule, the pro-rata rule, and the elimination of recharacterization.
When a conversion makes sense
A Roth conversion is most valuable when your tax rate at conversion is lower than your expected tax rate in retirement. Classic windows are: early retirement years before Social Security and RMDs kick in, a sabbatical or gap year, a year with large itemized deductions, or any year your income dips below normal. The bracket-filling strategy shows how to size each year's conversion.
Conversions can also be a powerful estate-planning tool. Roth IRAs have no lifetime RMDs, so the balance can continue compounding tax-free for decades, and heirs receive distributions tax-free as well (subject to the SECURE Act's 10-year payout rule).
How conversion tax actually works
The converted amount is reported on Form 1099-R and added to your taxable income as if it were ordinary wages. You pay tax at your marginal bracket — not a flat rate — which means a large conversion can push you into higher brackets and increase the average tax cost.
A smart strategy is to convert just enough to fill up your current bracket without spilling into the next one. For 2026, the 24% bracket runs to $206,700 for single filers; converting up to that ceiling can be far cheaper than triggering 32% rates.
The 5-year rule on converted dollars
Each conversion has its own 5-year clock. To withdraw the converted principal before age 59½ without a 10% penalty, you must wait five tax years from January 1 of the conversion year. This rule is separate from the 5-year rule for Roth earnings and separate again from the 5-year rule for inherited Roths.
If you're over 59½ at conversion, the 5-year rule on conversions does not apply to you — only the original 5-year rule on Roth earnings (measured from your first Roth contribution) remains relevant.
The pro-rata rule (critical for backdoor Roths)
If you own any pre-tax IRA balance — rollover IRA, SEP, SIMPLE, or deductible Traditional IRA contributions — the IRS aggregates them across all your non-Roth IRAs and treats every conversion dollar as a proportional mix of pre-tax and after-tax. You cannot cherry-pick to convert only the after-tax basis.
Many high earners zero out their pre-tax IRAs by rolling them into a current 401(k) before doing a backdoor Roth. The 401(k) is not counted in the pro-rata calculation, which restores a clean basis position.
Conversions are irreversible since 2018
The Tax Cuts and Jobs Act eliminated recharacterization for conversions effective 2018. Once you convert, you cannot undo it. This makes year-end conversions risky if your income is uncertain — many practitioners now spread conversions across the year and reassess in December.
Pay the tax with money from outside the IRA whenever possible. Using IRA funds to pay the tax bill reduces the amount actually getting Roth treatment and may trigger an additional 10% penalty if you're under 59½.
Frequently asked questions
How much tax will I pay on a Roth conversion?+
The converted amount is added to your ordinary income and taxed at your marginal rate. The calculator above estimates this based on the rate you input.
Can I undo a Roth conversion?+
No. The Tax Cuts and Jobs Act of 2017 eliminated recharacterization. Once executed, conversions are permanent.
Is there an income limit on Roth conversions?+
No. Conversions have no income limit — only contributions do. This is the basis of the backdoor Roth strategy.
Should I pay the tax from the IRA itself?+
Generally no. Paying from outside funds preserves more of the converted amount in the Roth and avoids a potential 10% early-withdrawal penalty if you're under 59½.
When is the deadline for a Roth conversion?+
December 31 of the tax year. Unlike contributions, conversions cannot be done in the following calendar year and applied retroactively.
