Backdoor Roth IRA: How the Two-Step Strategy Works

A backdoor Roth IRA is not a special account type. It is a common name for a two-step tax strategy used by some people whose income prevents them from making a normal direct Roth IRA contribution.

The basic sequence is:

1. Make a nondeductible contribution to a Traditional IRA.
2. Convert eligible IRA dollars to a Roth IRA.

The mechanics sound simple. The tax reporting can be much less simple, especially when other pre-tax IRA balances already exist.

Step 1: make a Traditional IRA contribution

Traditional IRA contribution eligibility is different from the ability to deduct that contribution.

A person may be able to contribute to a Traditional IRA even when income or workplace-plan participation prevents a current deduction.

For 2026, MFA's annual-rules engine uses an IRA contribution limit of $7,500 before any applicable catch-up amount.

When a contribution is nondeductible, it creates after-tax basis in the IRA. That basis must be tracked correctly so it is not taxed again when distributed or converted.

Step 2: convert to Roth

The next step is a Roth conversion.

A Roth conversion moves eligible retirement dollars from a Traditional IRA structure to a Roth IRA. The taxable portion of the conversion is generally included in income under the applicable rules.

If the Traditional IRA contains only the recent nondeductible contribution and there has been little or no growth, the taxable amount can be small.

But that clean example is not how every household looks.

The pro-rata rule is the part people miss

The IRS generally looks across your Traditional, SEP and SIMPLE IRA balances when determining the taxable and nontaxable portions of a conversion.

You generally cannot point to one specific IRA containing after-tax dollars and say, “Only convert these tax-free dollars while leaving all pre-tax IRA money untouched.”

The calculation considers the relationship between after-tax basis and the total applicable IRA balance.

Simplified example

Assume you have:

• $7,000 of nondeductible IRA basis;
• $93,000 of existing pre-tax IRA money;
• $100,000 total applicable IRA balance before the relevant year-end calculation.

Only about 7% of the aggregate amount represents after-tax basis.

A $7,000 Roth conversion would therefore not simply be treated as $7,000 tax-free in this simplified example. A substantial portion could be taxable because the conversion is allocated proportionally between pre-tax and after-tax dollars.

That is why a backdoor Roth discussion should start with “Do you have other pre-tax IRA balances?”, not merely “Is your income too high for a direct Roth contribution?”

Form 8606 matters

IRS Form 8606 is used for reporting items including nondeductible Traditional IRA contributions and certain Roth conversions.

This is not optional recordkeeping trivia. If after-tax basis is not tracked correctly, a future distribution or conversion can be reported incorrectly and potentially taxed twice.

Keep copies of prior Forms 8606 when carrying basis forward.

A rollover can change the pro-rata picture

Some employer plans accept incoming rollovers from Traditional IRAs.

Depending on the plan and the individual's facts, moving eligible pre-tax IRA dollars into a qualified employer plan can sometimes reduce the year-end pre-tax IRA balance used in the pro-rata calculation.

But do not move retirement money solely to make a backdoor Roth easier without comparing:

• plan fees;
• investment choices;
• creditor protections;
• distribution rules;
• future rollover options;
• whether the employer plan actually accepts the assets.

The retirement-account destination should still make sense on its own.

Conversion timing and investment movement matter

Suppose you contribute $7,000 to a Traditional IRA and the account grows to $7,300 before conversion.

The $300 of growth may be taxable when converted even if the original contribution was nondeductible.

This does not mean the strategy “failed.” It means the account had earnings before conversion and those earnings have their own tax treatment.

Likewise, trying to time a conversion around market movements can create complexity without guaranteeing a better outcome.

Spouses are separate taxpayers for IRA ownership

IRAs are individually owned accounts.

A married couple may each have their own IRA contribution and conversion decisions. The pro-rata calculation is generally tied to the individual's applicable IRA balances, not one combined household IRA pot.

That distinction can create different backdoor Roth results for two spouses in the same household.

Backdoor Roth is not the same as mega backdoor Roth

The names are similar, but the mechanics are different.

Backdoor Roth IRA: generally uses a nondeductible Traditional IRA contribution followed by a Roth IRA conversion.

Mega backdoor Roth: generally uses after-tax contributions inside an employer retirement plan followed by an in-plan Roth conversion or eligible rollover.

They involve different contribution limits, accounts and plan requirements.

When a direct Roth contribution is available

Do not use a complicated two-step strategy if a normal direct Roth IRA contribution is available and appropriate.

Roth IRA income eligibility rules change by tax year and filing status. Before using the backdoor process, check whether you actually need it for the current year.

A practical backdoor Roth checklist

Before executing anything:

1. Confirm current Roth IRA direct-contribution income rules.
2. Confirm the current IRA contribution limit.
3. Inventory every Traditional, SEP and SIMPLE IRA in your name.
4. Identify existing after-tax IRA basis from prior Forms 8606.
5. Decide whether any employer-plan rollover is appropriate independently of the tax strategy.
6. Make the contribution using the correct tax-year designation.
7. Keep records of the contribution and conversion.
8. Report the transactions correctly on the tax return.

The strategy is conceptually simple but tax-sensitive. The main blind spot is rarely the Roth account itself—it is the pre-tax IRA money already sitting elsewhere.