Backdoor Roth IRA: How It Works in 2026, Step by Step

A backdoor Roth IRA lets you fund a Roth even when your income is too high to contribute directly: in 2026 that means modified AGI of $168,000 or more for single filers or $252,000 or more for married couples filing jointly. You put up to $7,500 ($8,600 at age 50 or older) into a traditional IRA as a nondeductible contribution, then convert it to a Roth. Done cleanly, the conversion is almost tax-free. Done while you hold other pre-tax IRA money, the pro-rata rule can make most of it taxable. Here is the full sequence, the math, and the larger "mega backdoor" through a 401(k).

The Short Answer

• What it is: a nondeductible traditional IRA contribution followed by a Roth conversion. Traditional IRA contributions have no income limit, and conversions have had no income limit since 2010.
• Who uses it: people whose 2026 MAGI is at or above the top of the Roth phase-out ($168,000 single, $252,000 joint), or inside the phase-out and limited to a partial Roth contribution.
• How much: $7,500 for 2026, or $8,600 if you are 50 or older, per person.
• The trap: the pro-rata rule. The IRS looks at all your traditional, SEP and SIMPLE IRA balances on December 31 of the conversion year. If they hold pre-tax money, part of your conversion is taxable.
• The paperwork: Form 8606 every year you make a nondeductible contribution or convert. Skipping it carries a $50 penalty and, worse, can get your basis taxed twice.
• The bigger version: a mega backdoor Roth uses after-tax 401(k) contributions, up to the 2026 total plan limit of $72,000, but only if your plan allows it.

Who Needs a Backdoor Roth in 2026

Direct Roth IRA contributions phase out based on modified adjusted gross income. These are the 2026 ranges from IRS Notice 2025-67:

Source: IRS Notice 2025-67. The married-filing-separately range is not indexed for inflation.

The 2026 IRA contribution limit is $7,500, plus a $1,100 catch-up from age 50. That is one combined limit across all your traditional and Roth IRAs, so a $7,500 backdoor uses the whole year's allowance. You need taxable compensation (or a working spouse, covered below), but there is no upper age limit for traditional IRA contributions since 2020. Our 2026 Roth IRA contribution limits page covers the phase-out math for partial contributions.

Why bother for $7,500 a year? Roth money grows tax-free, comes out tax-free once distributions are qualified, and has no required minimum distributions for the owner. Our Roth IRA calculator projects what steady contributions grow to.

How to Do a Backdoor Roth, Step by Step

1. Check your other IRAs first. Add up every traditional, SEP and SIMPLE IRA you own (not your spouse's, not inherited ones). If the total is zero, or you can move it out by December 31 of the year you convert, the backdoor stays clean. If not, read the pro-rata section before going further.
2. Open a traditional IRA and a Roth IRA at the same custodian, then make a nondeductible contribution of up to $7,500 ($8,600 at 50+). For the 2026 tax year the deadline is the return due date without extensions, generally April 15, 2027. Leave it in cash or a money market fund so little or no earnings build up before you convert.
3. Convert to the Roth IRA. Ask for a trustee-to-trustee transfer or a same-custodian conversion. Any earnings between contribution and conversion are taxable, usually only a few dollars.
4. File Form 8606 with your return. Part I records the $7,500 nondeductible contribution as basis and runs the pro-rata calculation. Part II reports the conversion. With no other pre-tax IRA money, line 18 (the taxable amount) should be zero or close to it. Your custodian will send a Form 1099-R for the conversion; the 8606 is how you prove most of it was not taxable.
5. Keep the records. The IRS instructions say to keep your Forms 8606, 5498 and 1099-R until all distributions are made. A $100 penalty applies if you overstate nondeductible contributions.

Remember that conversions are permanent. Since 2018 you can no longer undo (recharacterize) a Roth conversion, so make sure the pro-rata math works before you convert.

The Pro-Rata Rule, With the Math

You cannot pick which dollars you convert. Form 8606 treats every dollar leaving your traditional IRAs as a mix of after-tax basis and pre-tax money, in the same proportion as your total. The key input is line 6: the value of all your traditional IRAs (including SEP and SIMPLE IRAs) on December 31 of the conversion year, not on the day you convert.

Hypothetical example. Mark earns $220,000 as a single filer, too much for a direct Roth contribution. He has a $67,500 rollover IRA from an old 401(k), all pre-tax. In 2026 he contributes $7,500 nondeductible and converts that $7,500 a week later. On December 31, 2026, the rollover IRA is still worth $67,500 (to keep the arithmetic simple, assume no growth).

Hypothetical. Line logic from IRS Form 8606 (2025); line 7 (other distributions) is zero in both cases.

Keeping the rollover IRA makes 90% of Mark's conversion taxable. At an assumed 24% marginal rate that is about $1,620 of tax on money he already paid tax on once, and the other $6,750 of basis stays stuck in the rollover IRA. The second column is why the fix below matters.

Two details catch people. First, the December 31 date means a rollover into an IRA later in the year (say, from a 401(k) when you leave a job in November) drags the conversion into pro-rata even though it happened afterward. Second, the rule is per person: your spouse's IRAs do not count against you.

How to Clear the Pro-Rata Problem

The standard fix is a reverse rollover: move the pre-tax IRA money into a workplace plan that accepts incoming rollovers, such as a 401(k), 403(b), governmental 457(b), or the federal Thrift Savings Plan. IRS Publication 590-A lists all of these as plans that can receive a traditional IRA rollover.

The tax code helps here. Only pre-tax money can go into the employer plan, and the IRS treats a rollover to a plan as made of taxable dollars first, as long as you leave at least your basis behind in the IRA. So the pre-tax balance moves to the plan, the after-tax basis stays in the IRA, and you convert that clean remainder. The move must be complete by December 31 of the conversion year.

Before you do it:

• Ask the plan whether it accepts IRA roll-ins. Not every plan does.
• Compare costs and funds. If the plan's funds are expensive, the Roth benefit may not be worth the switch.
• Federal employees: the TSP is one of the plans the IRS names as able to take a traditional IRA rollover. Our TSP vs 401(k) vs IRA comparison covers the trade-offs.

The alternative is to convert the pre-tax IRA money too and pay the tax now, a separate decision our traditional vs Roth IRA guide covers.

Is It Legal? Timing and the Step-Transaction Question

Yes. Each step is expressly allowed: anyone with compensation can make a nondeductible traditional IRA contribution, and the income limit on Roth conversions was repealed for tax years after 2009 by the Tax Increase Prevention and Reconciliation Act of 2005 (section 512).

The worry you will read about is the step-transaction doctrine, a court-made rule that can treat a series of steps as the single transaction they add up to: here, a direct Roth contribution by someone over the income limit.

Two facts are worth knowing. The IRS has not published a ruling, notice or regulation addressing the backdoor sequence. And the 2017 conference report on the Tax Cuts and Jobs Act (H.R. Rep. No. 115-466, page 289, footnotes 268 and 269) describes the strategy in plain terms: "Although an individual with AGI exceeding certain limits is not permitted to make a contribution directly to a Roth IRA, the individual can make a contribution to a traditional IRA and convert the traditional IRA to a Roth IRA." A committee report is legislative history, not law, but it is the clearest official statement on the subject.

No statute sets a waiting period between the two steps. Accurate reporting on Form 8606 matters more than the gap.

The Five-Year Rules

Two different five-year clocks apply, and they are often confused:

• The conversion clock (penalty). Each conversion starts its own five-year period on January 1 of the year you convert. If you are under 59½ and withdraw converted money before that period ends, the 10% additional tax can apply, but only to the part of the conversion that was taxable when you converted. In a clean backdoor almost nothing was taxable, so the exposure is small. Once you reach 59½, this clock no longer matters.
• The qualified-distribution clock (earnings). Earnings come out tax-free only after five years from January 1 of the first year you funded any Roth IRA, and only once you are 59½, disabled, or using the first-home exception (or your heirs inherit). This clock starts once, with your first Roth IRA of any kind, so opening a Roth early, even with a small amount, starts it sooner.

Withdrawals follow a fixed order: regular contributions first, then conversions (oldest first, taxable part before nontaxable part), then earnings.

Spousal Backdoor Roth

A spouse with little or no earned income can still do a backdoor Roth under the Kay Bailey Hutchison Spousal IRA rule, if you file jointly and your combined compensation covers both contributions. For 2026 a couple above $252,000 MAGI could move $15,000 into Roth IRAs this way ($17,200 if both are 50 or older).

Each spouse runs the steps in their own name, files a separate Form 8606, and has their own pro-rata calculation. A pre-tax IRA in your name does not spoil your spouse's conversion, and vice versa.

The Mega Backdoor Roth

The mega backdoor uses a 401(k) instead of an IRA and can move far more. It rests on a little-known kind of contribution: after-tax (non-Roth) employee contributions. They count toward the overall plan limit under Internal Revenue Code section 415(c), which is $72,000 for 2026 (or 100% of pay, if less). Catch-up contributions sit on top of that.

Hypothetical example. Dana, 45, earns $200,000 and defers the 2026 maximum of $24,500. Her employer adds $10,000. That leaves $72,000 − $34,500 = $37,500 of room for after-tax contributions, if the plan allows them. She then moves those dollars into Roth status in one of two ways:

• In-plan Roth conversion (an in-plan Roth rollover) into the plan's Roth 401(k) account. Since 2013 plans may allow this even for money you could not otherwise withdraw yet.
• In-service withdrawal to a Roth IRA. Under IRS Notice 2014-54 the after-tax contributions can go to a Roth IRA and the pre-tax earnings to a traditional IRA, from the same distribution.

Either way, earnings on after-tax contributions are pre-tax money, so they are taxed when converted. Converting soon after each contribution keeps that tax small. The IRS also notes that a partial withdrawal generally has to carry a proportional share of pre-tax amounts, so ask your plan how it accounts for after-tax money.

Federal employees: the TSP now offers Roth in-plan conversions of your traditional balance, with no income limit, and a conversion cannot be reversed. That converts pre-tax money, so the full amount is taxable, and the TSP withholds no tax, so you pay from other funds. It is a regular Roth conversion, not a backdoor. Our 2026 401(k) and TSP limits page has the deferral and catch-up figures, and Roth 401(k) vs Roth IRA compares the two Roth homes.

Later on, Roth money also shrinks the balance that drives required minimum distributions (see our RMD table), and heirs who inherit it follow the inherited IRA rules.

Sources & Methodology

• IRS Notice 2025-67, 2026 IRA limit, catch-up, Roth and deduction phase-out ranges, 401(k) deferral limit and the section 415(c) limit.
• IRS Form 8606 and Instructions for Form 8606, for the pro-rata calculation, per-spouse filing and penalties.
• IRS Publication 590-A (2025), contributions, nondeductible designation, spousal IRAs, conversions and rollovers from an IRA into an employer plan.
• IRS Publication 590-B (2025), the five-year rules, ordering rules and the end of recharacterization.
• Public Law 109-222, section 512, repeal of the income limit on Roth conversions.
• H.R. Rep. No. 115-466 (2017), conference report on the Tax Cuts and Jobs Act, page 289.
• IRS, 401(k) and profit-sharing plan contribution limits, and 26 CFR 1.415(c)-1, for what counts toward the $72,000 limit.
• IRS, Rollovers of after-tax contributions, Notice 2014-54 and Notice 2013-74, for the mega backdoor mechanics.
• TSP.gov, Roth in-plan conversions.

Method notes. All limits are 2026 figures. Examples with named people are hypothetical and use round numbers; the 24% rate is an assumption for illustration. Form 8606 line references are from the 2025 form, the latest final version; the calculation has worked the same way for years. 2027 limits had not been published when we checked.

This article is for general information and is not financial or tax advice. Figures are from the IRS, the Thrift Savings Plan and federal statute, checked against the primary sources on 2026-10-04. Backdoor and mega backdoor conversions depend on your full IRA picture and your plan's terms, so confirm the details with your custodian, plan administrator or a tax professional before converting.

FAQ

What is the income limit for a backdoor Roth IRA?
There is none. The income limits apply only to direct Roth contributions: for 2026, the phase-out runs from $153,000 to $168,000 for single filers and $242,000 to $252,000 for joint filers. Traditional IRA contributions and Roth conversions have no income cap.

What is the pro-rata rule?
When you convert, the IRS treats the converted dollars as a proportional mix of after-tax basis and pre-tax money across all your traditional, SEP and SIMPLE IRAs, valued on December 31 of the conversion year. Pre-tax IRA balances make part of the conversion taxable.

Does my 401(k) count for the pro-rata rule?
No. Only IRAs count: traditional, SEP and SIMPLE. Money in a 401(k), 403(b), 457(b) or the TSP is outside the calculation, which is why rolling pre-tax IRA money into one of those plans clears the problem.

How long should I wait between the contribution and the conversion?
No law sets a waiting period, and the IRS has not issued guidance on one. Converting soon after the contribution keeps taxable earnings small.

Do I need to file Form 8606 for a backdoor Roth?
Yes. It records the nondeductible contribution as basis and calculates how much of the conversion is taxable. Failing to file it when required carries a $50 penalty, and without it the IRS has no record of your basis.

What is the difference between a backdoor and a mega backdoor Roth?
A backdoor Roth goes through an IRA and is capped at the $7,500 IRA limit. A mega backdoor goes through a 401(k) using after-tax contributions, up to the $72,000 overall plan limit for 2026 minus your deferrals and employer money, and requires plan support.

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"Backdoor Roth IRA: How It Works in 2026, Step by Step." Wealthy Pot, 2026. https://wealthypot.com/backdoor-roth-ira/