A backdoor Roth IRA is not a special account — it is a two-step maneuver that gets money into a regular Roth IRA despite income limits that would otherwise block a direct contribution. Step one: contribute to a Traditional IRA on a nondeductible basis. Step two: convert that same money to a Roth IRA. Because conversions carry no income limit, this route is open to any earner, though one rule can quietly turn part of the conversion into a tax bill if you are not paying attention.
What changed in 2026
- The strategy remains fully intact at the federal level, with no income cap on Roth conversions, keeping the backdoor route open regardless of how high your income runs.
- Custodial platforms have streamlined the process, with several major brokerages offering a guided contribute-then-convert flow in one sitting.
- Roth IRA direct-contribution income limits keep adjusting for inflation, which affects who needs the backdoor route at all — check the current phase-out range before assuming you are blocked.
- Mega backdoor Roth interest has grown alongside the standard version, though that variant works through an employer 401(k) plan rather than an IRA and depends entirely on your plan allowing after-tax contributions and in-plan conversions.
The process, step by step
- Contribute to a Traditional IRA on a nondeductible basis. Do not claim a deduction on your tax return for this contribution — that is what keeps it eligible for tax-free conversion.
- File Form 8606 for the contribution year. This form establishes your basis — the after-tax amount the IRS already knows should not be taxed again.
- Convert the Traditional IRA balance to a Roth IRA, ideally soon after the contribution so little or no investment growth accumulates in between.
- Pay tax on any growth that occurred before conversion. If the money sat for a few weeks and earned a small return, that portion of the conversion is taxable; the contribution itself is not.
- File Form 8606 again for the conversion year, reporting the conversion and confirming how much of it was already-taxed basis versus new taxable growth.
- Repeat annually up to the IRA contribution limit each year, since the backdoor route does not have its own separate limit — it uses the standard IRA cap.
The pro-rata rule, explained
This is the step most explainers underplay. The IRS treats all of your Traditional, SEP, and SIMPLE IRA balances as one combined pool when you convert — not just the account you just funded. If you already hold pre-tax IRA money elsewhere, only a proportional slice of any conversion counts as tax-free basis; the rest is taxed as income.
A hypothetical example: say you have $18,000 in pre-tax Traditional IRA money from an old rollover, and you add a $2,000 nondeductible contribution and convert that $2,000. The IRS does not let you convert just the $2,000 tax-free — it looks at the full $20,000 pool and treats only 10% of any conversion as tax-free basis. Converting $2,000 in that scenario would mean roughly $1,800 counts as taxable income, not $0.
The common fix: if your employer 401(k) accepts incoming rollovers, moving pre-tax IRA money into the 401(k) first clears the IRA of pre-tax balances, leaving only the nondeductible contribution to convert cleanly.
Common mistakes
Ignoring existing pre-tax IRA balances. The pro-rata rule applies to the total of all your Traditional-type IRAs, not just the one funded for the backdoor conversion.
Letting the money sit and grow before converting. Any earnings that accrue between the contribution and the conversion are taxable in the year of conversion, so converting promptly limits the tax bite.
Forgetting Form 8606. Without it on record, the IRS has no way to know part of your IRA is already-taxed basis, risking double taxation down the road.
Confusing this with the mega backdoor Roth. The mega version runs through an employer 401(k)'s after-tax contribution feature, not an IRA, and depends entirely on plan rules — the two strategies are related but not interchangeable.
FAQ
Is the backdoor Roth IRA legal?
Yes. It is a well-established use of two ordinary IRA rules — nondeductible contributions and unlimited conversions — that the IRS has acknowledged for years through its own tax forms.
Do I owe tax on a backdoor Roth conversion?
Only on any growth that occurred before conversion, or on the portion attributable to pre-tax IRA balances under the pro-rata rule. The original nondeductible contribution itself is not taxed again.
Can I undo a Roth conversion?
No. Roth conversions have not been reversible since a law change several years ago, so confirm the tax impact before converting.
How is this different from a Roth conversion ladder?
A backdoor Roth moves new after-tax contributions into a Roth right away. A Roth conversion ladder converts existing pre-tax retirement savings over several years, usually to access the money before 59 and a half.
Where to go next
For the broader Roth-versus-Traditional decision this strategy sidesteps, see Roth vs Traditional IRA in 2026. If you are opening your first Roth IRA rather than working around income limits, read how to start a Roth IRA in 2026, and for the multi-year version of a conversion, see Roth conversion ladder explained for 2026.