The backdoor Roth IRA, explained step by step

A backdoor Roth IRA is a way to get money into a Roth IRA when your income is too high to contribute directly. You put money into a traditional IRA without taking a tax deduction, then convert it to a Roth IRA. Done cleanly, there's little or no tax on the conversion. The catch is the pro-rata rule: if you already have pre-tax money in any traditional IRA, part of the conversion becomes taxable.

It sounds like a loophole, and the name doesn't help. It's really two ordinary, long-standing moves done back to back, each with its own IRS form line. This guide walks through who it's for, the steps, the rule that trips people up, and a made-up example you can follow.

This is general education, not tax or financial advice. The IRS publications linked below, tax software or a tax preparer can confirm how it works for you.

uFIRE is for education only, not financial advice. Figures checked October 26, 2026 against IRS.gov: news release IR-2025-111 (2026 limits), Publication 590-A (2025), Publication 590-B (2025) and the 2025 Instructions for Form 8606. The 2027 limits usually come out in October or November; we'll update this guide when they do.

Who a backdoor Roth is for

A backdoor Roth only makes sense if a direct Roth IRA contribution is off the table, or only partly allowed, because of your income. Here are the 2026 ranges:

Source: [IRS news release IR-2025-111](https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500).

If your income is under the first line, you don't need any of this. Contribute to a Roth IRA directly. Our guide to Roth vs traditional can help you decide whether Roth is the right fit at all.

It also helps to look at your workplace plan first. Roth 401(k) contributions have no income limit, and the 401(k) limit is much bigger ($24,500 in 2026). If you haven't captured your full employer match yet, that usually comes first (which account do you save in first?).

How it works, step by step

Step 1: make a nondeductible traditional IRA contribution

Anyone with earned income can contribute to a traditional IRA, whatever they earn. What income changes is whether you can deduct it. If you're covered by a retirement plan at work, the 2026 deduction phases out between $81,000 and $91,000 for single filers and between $129,000 and $149,000 for married couples filing jointly (IRS). Above those lines, your contribution goes in after tax. That after-tax amount is called your basis.

You can make a 2026 contribution any time up to the tax filing deadline in 2027, not including extensions (IRS Publication 590-A). When you contribute between January 1 and that deadline, tell your provider which year it's for.

Step 2: convert it to a Roth IRA

Ask your provider to move the money from the traditional IRA to a Roth IRA. Most people use a direct transfer between accounts at the same provider, which avoids the 60-day rollover window entirely.

When you convert, you include in income only the part that hadn't already been taxed (IRS Publication 590-A). Your basis comes across tax-free. Any growth while the money sat in the traditional IRA is taxable. That's why many people convert soon after contributing, and leave the money in cash or a money market fund until they do.

Step 3: report it on Form 8606

Form 8606 is where both halves are recorded: the nondeductible contribution in one part, and the conversion in another (Form 8606 instructions). It's how the IRS knows that money was already taxed. If you're married, each spouse who does a backdoor Roth files their own Form 8606.

The penalty for not filing a required Form 8606 is $50, and $100 for overstating nondeductible contributions, unless you can show reasonable cause. The bigger risk is quieter: without the form, you have no record of your basis, and you could end up paying tax twice on the same money.

The pro-rata rule: the part that trips people up

You can't pick and choose which dollars you convert. When you convert any money from a traditional IRA, the IRS looks at the value of all your traditional IRAs together, including SEP IRAs and SIMPLE IRAs, and treats the conversion as a proportional slice of all of it (Form 8606 instructions, IRS Publication 590-B).

The balance used is the value as of December 31 of the year you convert, plus what you converted or took out during the year. So it doesn't matter whether the old money and the new contribution sit in different accounts or with different providers.

What doesn't count:

• 401(k), 403(b), governmental 457(b) and Thrift Savings Plan balances
• Roth IRAs
• Your spouse's IRAs (each person's figures are separate)

A made-up example: the clean case

Sam (invented for this guide) is single, has a 401(k) at work and earns $185,000 a year, too much for a direct Roth contribution. Sam has no other IRAs.

In February 2026, Sam puts $7,500 into a new traditional IRA, takes no deduction, and leaves it in cash. A week later, Sam converts the whole account, which has earned $5 of interest, to a Roth IRA.

Sam reports $5 of extra income and now has $7,505 in a Roth IRA.

The same move, with an old rollover IRA

Now say Sam also has $67,500 in a rollover IRA from a previous job, all pre-tax money, and it's still there on December 31. For simplicity, ignore growth.

Sam paid tax on the $7,500 going in, and now owes tax on $6,750 of the conversion too. The remaining $6,750 of basis isn't lost: it stays in the rollover IRA and is tracked on Form 8606 for the future. But the "backdoor" didn't do what Sam hoped this year.

Ways people handle old IRA money

• Roll it into a workplace plan. Many 401(k) plans accept roll-ins of pre-tax IRA money. If it's out of the IRA by December 31, it no longer counts in the pro-rata calculation. Check your plan's rules, fees and investment choices first.
• Convert it all. Some people convert the old IRA too, paying tax on it, often across several lower-income years. That's a bigger decision. Our guide to Roth conversions and IRMAA covers the trade-offs.
• Skip the backdoor. If neither fits, a taxable brokerage account or a bigger Roth 401(k) contribution can do a similar job.

Things to know before you start

• There's no undo. Conversions made in 2018 or later can't be recharacterized as traditional IRA money (IRS Publication 590-A). Check the pro-rata math before you convert, not after.
• Each conversion has its own five-year clock for the 10% additional tax if you withdraw the taxable part before 59½ (IRS Publication 590-B). If almost nothing was taxable, as in Sam's clean case, this matters little. Getting to your money before 59½ explains the clock.
• Contribution limits still apply. The $7,500 is shared across all your IRAs. Putting in more than the limit can mean a 6% excise tax each year it stays there.
• You need earned income (or a working spouse, if you file jointly) to contribute to any IRA.
• Keep records. Save each year's Form 8606, your contribution confirmation and your provider's Form 1099-R and Form 5498. They're your proof of basis, sometimes decades later.

Why FIRE savers care

Money in a Roth IRA grows tax-free, has no required minimum distributions for the original owner, and the amount you put in through conversions becomes reachable before 59½ once each five-year clock runs out. For people planning to stop work early, that's flexible money for the bridge years. A backdoor Roth adds $7,500 a year to that pile for people who'd otherwise be shut out.

It's one tool, not a requirement. Saving steadily in whatever account you can use matters far more than which door the money goes through.

A simple plan for this month

1. Estimate your 2026 modified AGI and check it against the table above.
2. List every IRA you have, including old rollover, SEP and SIMPLE IRAs, with today's balances.
3. If those balances are all zero (or Roth), a backdoor Roth is likely clean. If not, look at whether your 401(k) accepts roll-ins.
4. Pick a quiet week to contribute and convert, and keep the confirmations.
5. Tell your tax preparer, or flag it in your software, so Form 8606 gets filed.

Common questions

Is a backdoor Roth IRA legal?

Yes. It's two separate, permitted steps: a nondeductible contribution to a traditional IRA, and a conversion to a Roth IRA. Both are described in IRS Publication 590-A and reported on Form 8606. What matters is reporting them correctly and understanding how the pro-rata rule applies to you.

What are the Roth IRA income limits for 2026?

For 2026, the amount you can contribute directly to a Roth IRA phases out with modified AGI between $153,000 and $168,000 for single filers and heads of household, and between $242,000 and $252,000 for married couples filing jointly. If you're married filing separately and lived with your spouse during the year, it phases out between $0 and $10,000.

Do I pay tax on a backdoor Roth conversion?

You pay tax only on the part of the conversion that hadn't been taxed before. If your only traditional IRA money is the nondeductible contribution you just made, that's usually just any small growth before you converted. If you also have pre-tax money in any traditional, SEP or SIMPLE IRA, the pro-rata rule makes part of the conversion taxable.

Does my 401(k) count in the pro-rata rule?

No. The calculation uses only your traditional, SEP and SIMPLE IRA balances as of December 31. Workplace plans like 401(k)s, 403(b)s, 457(b)s and the TSP don't count, which is why some people roll old IRA money into their workplace plan first.

How long should I wait between contributing and converting?

The IRS doesn't set a waiting period in Publication 590-A. Many people convert within days, so there's little growth to be taxed. If you're unsure, a tax preparer can tell you what they recommend for your situation.

What happens if I forget to file Form 8606?

There's a $50 penalty for not filing a required Form 8606, unless you can show reasonable cause. You can usually file it late. The bigger problem is losing the record of your after-tax basis, which could lead to paying tax twice on the same money later.

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