What is a Backdoor Roth IRA?

A Backdoor Roth IRA is not a special account type. It is a two-step maneuver that lets high earners fund a Roth IRA despite exceeding the income limits: contribute to a traditional IRA on a nondeductible basis, then convert that balance to a Roth IRA. Conversions have no income limit, so the front door being closed does not matter.

The strategy exists because of an inconsistency in the tax code. Congress removed the income cap on Roth conversions in 2010 but left the cap on direct Roth contributions in place, which made the workaround available to anyone willing to do the paperwork.

Who Needs It

Direct Roth IRA contributions phase out over an income range. For 2026:

Below the range you can contribute directly and have no reason to use the backdoor. Inside the range your allowed contribution is reduced. Above it, direct contributions are barred entirely and the backdoor is the only route.

The 2026 IRA contribution limit is $7,500, plus a $1,100 catch-up if you are 50 or older. Those limits apply to the contribution step, so the backdoor moves the same amount a direct contribution would.

How It Works

1. Contribute to a traditional IRA and do not deduct it. If your income is high enough to need the backdoor, you likely cannot deduct it anyway.
2. Convert to a Roth IRA. Most custodians handle this in a few clicks.

Then there is the paperwork, which is not optional. File Form 8606 for both the year of the contribution and the year of the conversion. It records your after-tax basis and is what prevents the same dollars being taxed twice; skipping it is the most common and most expensive backdoor Roth mistake.

Because the contribution was already after-tax, converting it produces little or no additional tax. Any investment earnings between contribution and conversion are taxable, which is why many people convert promptly and leave the money in cash in between.

The Pro-Rata Rule Is the Catch

This is where backdoor Roth attempts go wrong, and the damage is not obvious until you file.

The IRS does not let you choose which dollars you convert. Under the pro-rata rule, every conversion is treated as coming proportionally from all your traditional, SEP, and SIMPLE IRA balances combined, measured on December 31 of the conversion year. Employer 401(k) balances are excluded.

Say you have $93,000 in a rollover IRA from an old 401(k), all pre-tax, and you contribute $7,500 nondeductible intending a clean backdoor conversion. Your total IRA balance is $100,500, of which $7,500 (7.5%) is after-tax basis. Converting $7,500 means only about $560 comes out tax-free. The remaining $6,940 is taxable income, and you still carry basis forward on the rest.

The usual fix is to eliminate the pre-tax IRA balance before converting, typically by rolling it into your current employer’s 401(k) if the plan accepts incoming rollovers. Since 401(k) balances are invisible to the pro-rata calculation, this restores a clean conversion. The rollover must be completed before December 31 of the conversion year, not merely before the conversion.

Backdoor Roth vs. Mega Backdoor Roth

Similar names, different mechanisms and very different scale.

They are not mutually exclusive. Someone whose plan supports both can do each in the same year.

Is It Legal?

Yes. The concern raised for years was the step transaction doctrine, the idea that the IRS might collapse the contribution and conversion into a single disallowed direct Roth contribution. That has not happened. The conference report accompanying the 2017 tax law explicitly acknowledged the strategy, and there is no statutory waiting period between the two steps.

Legislation to close the backdoor has been proposed and not enacted. That is worth knowing when planning multi-year, since the rule could change.

Frequently Asked Questions

How much can I put into a backdoor Roth? The standard IRA limit, $7,500 for 2026, plus $1,100 if you are 50 or older. The backdoor changes how you get the money in, not how much.

How long should I wait between contributing and converting? There is no required waiting period. Many people convert within days. Waiting longer only creates taxable earnings on the contribution.

What if I already have a large traditional IRA? The pro-rata rule will make most of your conversion taxable. Roll the pre-tax balance into an employer 401(k) before December 31 of the conversion year if your plan accepts it, or reconsider the strategy.

Do I need to file anything? Form 8606, for both the contribution year and the conversion year. Skipping it is the most common backdoor Roth error and results in paying tax twice on the same dollars.

Can I do a backdoor Roth for my spouse? Yes. Each spouse uses their own IRA, and a non-working spouse can contribute through a spousal IRA based on household earned income. Pro-rata is calculated per person, not jointly.

Does a backdoor Roth conversion have a five-year clock? Yes. Each conversion carries its own five-year period before the converted amount can be withdrawn penalty-free if you are under 59 1/2. This rarely matters if you are contributing for the long term, but it matters for early retirees.