Not the mega backdoor Roth
If you've read about the mega backdoor Roth, forget it for a minute. That strategy depends on a specific 401(k) plan feature that most employers don't offer, and it can move tens of thousands of dollars a year into Roth space.
The regular backdoor Roth IRA is different and far more widely usable. It doesn't touch your 401(k) at all. It uses a traditional IRA, an account type anyone with earned income can open regardless of what their employer offers, and it's limited to the standard annual IRA contribution amount rather than a much larger 401(k)-based figure. If you've maxed a 401(k) and want more Roth space, or if you simply earn too much to contribute to a Roth IRA directly, this is the strategy for you. If your employer's 401(k) happens to support after-tax contributions and in-plan conversions, the two strategies can be done in the same year, but they're independent of each other.
Why you'd need a backdoor at all
A Roth IRA is normally simple: contribute after-tax money, let it grow, withdraw tax-free in retirement. The complication is that the IRS phases out direct Roth IRA eligibility at higher incomes.
According to the IRS's November 2025 announcement of 2026 retirement plan limits, the income phase-out range for direct Roth IRA contributions is $153,000 to $168,000 of modified adjusted gross income for single filers and heads of household, and $242,000 to $252,000 for married couples filing jointly. Below the bottom of the range, you can contribute the full amount. Inside the range, your allowed contribution shrinks proportionally. Above the top of the range, you can't contribute to a Roth IRA directly at all.
The same IRS announcement set the 2026 contribution limit for traditional and Roth IRAs combined at $7,500, up from $7,000 in 2025, with an additional $1,100 catch-up contribution for people 50 and older, for a total of $8,600.
Here's the part that makes the backdoor route possible: there's no income limit on contributing to a traditional IRA on a non-deductible basis, and no income limit on converting a traditional IRA to a Roth IRA. The income limit only applies to contributing to a Roth IRA directly. Combine a non-deductible traditional IRA contribution with an immediate conversion, and you've functionally gotten money into a Roth IRA despite an income well above the direct contribution limit.
The steps
1. Confirm you actually need this route. If your income is below the bottom of the phase-out range for your filing status, just contribute to a Roth IRA directly. The backdoor process adds a filing requirement and a pro-rata risk (more on that below) for no benefit if you don't need it.
2. Open a traditional IRA, or use an existing empty one. Most brokerages let you open one online in a few minutes. If you already have a traditional IRA holding pre-tax money from an old 401(k) rollover or a deductible contribution in a prior year, read the pro-rata section before you do anything else. It changes the math significantly.
3. Make a non-deductible contribution. Contribute up to the annual limit, $7,500 for 2026 or $8,600 if you're 50 or older. When you file taxes for the year, you won't take a deduction for this contribution, since your income is too high to qualify for one if you're also covered by a workplace retirement plan (or your spouse is). This is what makes the contribution "non-deductible" rather than a normal traditional IRA contribution.
4. Let the contribution settle, then convert. There's no legally required waiting period between the contribution and the conversion; the IRS clarified informally in 2018 that the step transaction doctrine doesn't apply to this sequence. In practice, most people wait until the cash contribution clears in the account, often just one business day, then convert the full balance to a Roth IRA through their brokerage's conversion tool. Converting quickly matters for one reason: any growth that happens in the traditional IRA between contribution and conversion is taxable at conversion, since it wasn't part of your after-tax basis.
5. File Form 8606. This is the step people skip, and it's the one that actually makes the strategy work on paper. Form 8606 reports the non-deductible contribution (Part I) and the conversion (Part II), establishing your after-tax basis so the IRS doesn't tax the same dollars twice. Without it, the IRS has no record that you already paid tax on the contribution, and the entire conversion can look taxable on review. File it for every year you make a non-deductible contribution or convert one, even if your tax software doesn't prompt you clearly to do so.
A clean worked example
Priya is 38, single, and earns $190,000, well above the $168,000 top of the 2026 Roth IRA phase-out range for single filers. She has no other traditional, SEP, or SIMPLE IRA balances anywhere.
In January, Priya opens a new traditional IRA and contributes $7,500, the full 2026 limit for someone under 50. She doesn't deduct the contribution on her tax return. Two business days later, once the deposit has settled, the account has grown slightly to $7,512 from a money market sweep. She converts the entire balance to a Roth IRA.
At tax time, Priya files Form 8606. Her basis is $7,500, and her conversion was $7,512, so $12 is taxable as ordinary income and $7,500 is not. She now has $7,512 inside a Roth IRA, tax-free going forward, despite an income far above the direct contribution limit.
The pro-rata rule: the actual trap
Priya's example worked cleanly because she had no other traditional IRA money. Most backdoor Roth mistakes happen because people don't have that clean setup and don't realize it matters.
The IRS doesn't let you convert only the after-tax portion of your IRA money if you hold other pre-tax IRA balances. Under the aggregation rule in Internal Revenue Code Section 408(d)(2), all of your traditional, SEP, and SIMPLE IRAs are treated as one combined account for the purpose of figuring out how much of any conversion is taxable, regardless of which specific account the money moves out of. Every conversion pulls out a proportional mix of pre-tax and after-tax dollars, not the after-tax dollars you intended to isolate.
Take Marcus. He's 45, earns $210,000, and rolled a $93,000 balance from an old 401(k) into a traditional IRA a few years ago, entirely pre-tax money he never paid tax on. This year he opens a new contribution slot in that same traditional IRA (or a separate one; the IRS aggregates across all of them) and contributes $7,500 non-deductible, intending to convert just that $7,500 to Roth.
His total traditional IRA balance across all accounts is now $100,500 ($93,000 pre-tax plus $7,500 after-tax basis). His after-tax percentage of the total is $7,500 divided by $100,500, about 7.5%. When he converts $7,500, only about 7.5% of it, roughly $560, is treated as tax-free basis. The remaining $6,940 is taxed as ordinary income, even though he only meant to convert the money he'd already paid tax on. The pre-tax and after-tax dollars aren't separable once they're aggregated; the IRS taxes the conversion proportionally no matter which account the cash physically comes from.
This is the single most common mistake people make with this strategy: assuming they can convert "just the new contribution" when an old rollover IRA is sitting in the background. If you're in Marcus's position, one common way to avoid the pro-rata hit is rolling the pre-tax balance into a current employer's 401(k), if the plan accepts incoming rollovers, before doing the backdoor conversion. That empties the pre-tax IRA pool and leaves only the new after-tax contribution to convert. It's worth checking whether an old 401(k) you're already counting toward your net worth could be rolled into a current plan for this reason, well before you attempt a backdoor conversion.
Is the backdoor Roth IRA still legal?
Yes, and this comes up because a 2021 legislative proposal briefly threatened it. The Build Back Better Act, as drafted in the House in late 2021, included a provision that would have eliminated backdoor Roth conversions for high earners starting in 2022. The bill never passed the Senate; Senator Joe Manchin withdrew his support in December 2021, and the provision died with it. No subsequent legislation, including the tax law changes enacted in 2025, has restricted or eliminated the backdoor Roth IRA. As of 2026, it remains a fully legal use of two IRS-permitted transactions: a non-deductible contribution and a Roth conversion.
Congress could revisit the idea in future tax legislation, and it's worth watching if you rely on this strategy every year, but no current law limits it.
Where the backdoor Roth fits in a broader plan
The backdoor Roth IRA is generally a later-stage move, something to layer in after you've captured any employer 401(k) match and covered the more foundational steps in your savings order of operations. It's also worth doing every year you're above the income limit and have the cash available, since the $7,500 (or $8,600) window doesn't carry over if you skip a year.
Once the money is in the Roth IRA, it behaves like any other Roth IRA balance for net worth purposes: it's an asset, it belongs on your balance sheet at current market value, and tracking it monthly alongside your other accounts is what actually shows the strategy compounding over time. A tracker like Steady Wealth logs the account balance the same way it logs any IRA, so the mechanics of how the money got there stay separate from the number you watch grow.
Frequently asked questions
Is the backdoor Roth IRA legal?
Yes. It combines two transactions the IRS explicitly permits: a non-deductible contribution to a traditional IRA and a conversion of a traditional IRA to a Roth IRA. A 2021 legislative proposal would have banned it, but that bill never passed, and no law since has restricted it.
What is the pro-rata rule and how do I avoid it?
The pro-rata rule requires the IRS to treat all of your traditional, SEP, and SIMPLE IRA balances as one combined pool when calculating how much of a conversion is taxable, even if you only intended to convert a specific after-tax contribution. You can't cherry-pick which dollars convert. The main way to avoid it is having zero pre-tax balance in any traditional, SEP, or SIMPLE IRA at year end, which sometimes means rolling old pre-tax IRA money into a current employer's 401(k) first, if that plan accepts rollovers.
Do I need to do this every year?
The strategy resets annually. There's no carryover if you skip a year, so if your income is consistently above the Roth IRA phase-out range and you want the contribution space, you generally need to repeat the non-deductible contribution and conversion each year.
What if I already have money in a traditional IRA from an old 401(k) rollover?
That balance will be included in the pro-rata calculation and will make part of your conversion taxable, proportional to how much of your total traditional IRA balance is pre-tax. Check whether your current employer's 401(k) plan accepts incoming rollovers before doing the backdoor conversion; moving the old pre-tax balance into the 401(k) removes it from the pro-rata pool.
How long do I have to wait between the contribution and the conversion?
There's no legally required waiting period. The IRS informally addressed this in 2018 and the step transaction doctrine is not considered a risk for this sequence by tax professionals. Most people convert as soon as the contributed cash settles in the account, which limits how much investment growth becomes taxable at conversion.
Does the backdoor Roth IRA affect my current year's tax bill?
The non-deductible contribution itself doesn't reduce your taxable income, since you don't take a deduction for it. If you convert quickly, before meaningful growth accumulates, there's typically little or no additional tax owed at conversion beyond what the pro-rata rule requires. Filing Form 8606 is what documents the non-taxable basis to the IRS; skipping it risks the IRS treating the entire conversion as taxable.