Backdoor Roth IRA: How It Works and Who Should Use It

What a Backdoor Roth IRA Actually Is

A backdoor Roth IRA isn’t a special account — it’s a two-step maneuver. You contribute money to a traditional IRA (which has no income limit), then convert that money to a Roth IRA (which does have income limits, but conversions don’t). The result is money sitting in a Roth account, growing tax-free, even though your income would normally have blocked you from contributing to a Roth directly.

The reason this workaround exists at all: the IRS caps direct Roth IRA contributions based on your modified adjusted gross income (MAGI). For 2026, the IRS phases out direct Roth contributions for single filers with MAGI between $153,000 and $168,000, and for married couples filing jointly between $242,000 and $252,000 (IRS Notice 2025-67). The IRS adjusts these ranges for inflation most years. Above the top of that range, you can’t contribute to a Roth IRA directly at all.

There’s no income limit on traditional IRA contributions or on Roth conversions, which is the loophole this strategy relies on. It’s legal, it’s been around for over a decade, and no legislation prohibiting it has been enacted — but the mechanics have a few sharp edges, especially if you already have other pre-tax IRA money sitting around.

Time commitment: the actual steps take maybe 20 minutes per year if your brokerage handles it online. The part that takes longer is figuring out whether you qualify cleanly, and filing one extra tax form.

Before You Start: Gather These

Your 2026 MAGI estimate. You need to know whether you’re actually over the Roth contribution limit, since if you’re not, you don’t need this strategy — just contribute directly.
A list of every traditional, SEP, and SIMPLE IRA you own. This matters more than people expect; more below.
Your account login for a brokerage that offers both IRA types (most major ones do — Fidelity, Schwab, Vanguard, etc.).
Last year’s tax return, specifically to check if you filed Form 8606 before (it tracks “basis” in nondeductible IRA contributions).
A tax preparer or software that handles Form 8606 correctly. Not all consumer software does this well on the first pass; you may need to enter it manually.

The Step-by-Step Process

1. Open a traditional IRA (if you don’t already have one).
Most brokerages let you open this online in under 10 minutes. If you already have a traditional IRA with existing pre-tax balances, don’t open a new one to “start fresh” — the IRS treats all your traditional IRAs as one combined pot for tax purposes, so a new empty account doesn’t avoid that issue.

2. Contribute the nondeductible amount.
For 2026, the contribution limit is $7,500 if you’re under 50, plus a $1,100 catch-up contribution if you’re 50 or older, for a total of $8,600. The IRA catch-up amount is indexed for inflation under the SECURE 2.0 Act and rose from $1,000 in 2025 to $1,100 for 2026. Make this a nondeductible contribution, since at high income you likely can’t deduct it anyway. Your brokerage will ask or you’ll note it on Form 8606 at tax time either way.

3. Do not invest the money yet — or if you do, expect some gain or loss.
Some people convert same-day to avoid any investment growth (which would be taxable). Others leave it a few days. There’s no required waiting period, but the longer the money sits invested in the traditional IRA, the more likely it earns a small amount, which becomes taxable income upon conversion.

4. Convert the traditional IRA balance to a Roth IRA.
Inside your brokerage account, this is usually a transfer request between your own two accounts, not a withdrawal. Look for “Convert to Roth” under account actions, or call your brokerage if you can’t find it. You’ll see a confirmation and a 1099-R will be generated for that tax year, reporting the conversion to the IRS.

5. Report it correctly on Form 8606 at tax time.
This is the step people skip, and it’s the one that actually tells the IRS “this was already-taxed money, don’t tax it again.” File Form 8606 for the year you contributed and again for the year you converted — sometimes the same year, sometimes not, depending on timing. If your tax software doesn’t prompt for it, you may need to enter it manually.

What it looks like when it goes wrong: you get a 1099-R showing a distribution, and if you don’t file Form 8606, your return (or software) may treat the whole conversion as taxable income, since the IRS has no other record that you already paid tax on that contribution. If that happens, file or amend with Form 8606 attached, with your contribution records as backup.

The Pro-Rata Rule: Where This Trips People Up

Here’s the part that causes the most expensive mistakes. The IRS doesn’t let you convert “just the nondeductible part” if you have other pre-tax money in any traditional, SEP, or SIMPLE IRA. It treats all your traditional-type IRA balances as one combined account for this calculation — this is called the pro-rata rule.

Example: Say you have $93,000 sitting in a traditional IRA from an old 401(k) rollover, all pre-tax. You contribute $7,500 nondeductible and convert that $7,500 to Roth. The IRS doesn’t see it as converting “your” $7,500 — it sees your total traditional IRA balance as $100,500, of which $7,500 (about 7.5%) is after-tax basis. So only about 7.5% of your conversion is tax-free; the other 92.5%, roughly $6,940, is taxable income in the year you convert.

This rule applies even if the pre-tax money is in a completely separate account at a different brokerage. It does not apply to money sitting in an employer 401(k) or 403(b) — those don’t count toward the pro-rata calculation. That’s why some people roll their old traditional IRA balances into a current employer’s 401(k) (if the plan accepts incoming rollovers) before doing a backdoor Roth, to clear the IRA side down to zero first.

Mistakes That Cause Tax Surprises or Delays

Ignoring old rollover IRAs. This is the single biggest cause of a backdoor Roth going sideways. Check every traditional, SEP, and SIMPLE IRA you hold anywhere before you convert a dollar.
Forgetting to file Form 8606. Without it, there’s no paper trail showing your basis, and you — or your heirs — may end up paying tax twice on the same money someday.
Converting in a different year than you contributed, without tracking it. It’s fine to contribute in December and convert in January, but you need to report the contribution on the prior year’s 8606 and the conversion on the following year’s.
Letting the money grow before converting. Any earnings between contribution and conversion are taxable. Keeping the window short (same day to a few days) keeps this simple.
Assuming the 5-year rule doesn’t apply. Each Roth conversion has its own 5-year clock for penalty-free withdrawal of converted amounts if you’re under 59½. This mostly matters if you might need the money early — for long-term retirement savings it rarely changes your plan.
Doing this while also planning to deduct a traditional IRA contribution elsewhere. You can’t double-dip; track exactly which dollars were deducted and which weren’t.

Who This Actually Makes Sense For

This strategy exists for people whose income is too high for direct Roth contributions but who still want Roth-style tax-free growth. It’s most worth the paperwork for people who:

Expect to be in the same or a higher tax bracket in retirement than they are now (otherwise a traditional IRA or 401(k) deduction might serve them better).
Don’t have large pre-tax IRA balances elsewhere, which keeps the pro-rata math simple or avoidable.
Have already maxed out a 401(k) or 403(b) match and want additional tax-advantaged room.

It’s less useful for people with large existing traditional IRA rollovers who can’t or won’t move that money into a 401(k) first — the pro-rata tax bill can eat much of the benefit. In that case, it’s worth running the actual numbers with a tax preparer before converting, since the upfront tax cost is sometimes larger than people expect.

Checking Your Work and What Happens Next

After you convert, watch for two documents the following January: a 1099-R from your brokerage reporting the conversion, and your own copy of Form 8606 once you or your preparer files it. Keep both indefinitely — Form 8606 is cumulative, meaning each year’s form references your running total of nondeductible basis, and you’ll want that history if you ever convert again or take distributions.

If you’re unsure whether your prior-year filings included Form 8606, you can request a tax return transcript from the IRS at IRS.gov (available for the current and three prior tax years) to see the forms and schedules filed with your return, or check with whoever prepared your return. There’s no separate “approval” step from the IRS for a backdoor Roth — it isn’t a program you apply to. It’s simply reported correctly or not, and getting it right at tax time is what keeps the conversion tax-free the way you intended.

Sources

IRS.gov — Retirement Topics: IRA Contribution Limits
IRS.gov — Roth IRAs
IRS.gov — Instructions for Form 8606
IRS.gov — Retirement Topics: Amount of Roth IRA Contributions That You Can Make

This article is for general information only and is not financial, legal, or tax advice. Program rules change and vary by state — always confirm details with the official agency (.gov) before acting.