The Backdoor Roth IRA: Step by Step Guide

Why the Backdoor Exists at All

Direct Roth IRA contributions phase out above certain income levels, which shuts out many high earners. But there is no income limit on contributing to a traditional IRA on a nondeductible basis, and no income limit on converting a traditional IRA to a Roth. String those two facts together and you have the backdoor Roth: a perfectly legal path that lets high earners fund a Roth indirectly.

The maneuver has been widely used and openly acknowledged for years. It is not a loophole so much as a known workaround built into how the rules interact. The contribution amount is still capped at the normal annual IRA limit, so check current IRS figures; the backdoor changes who can contribute, not how much.

The Two-Step in Practice

Mechanically, the backdoor Roth is two moves done close together. First, you contribute to a traditional IRA and, because your income is too high to deduct it, the contribution is nondeductible after-tax money. Second, you convert that traditional IRA to a Roth IRA. Since the contribution was already taxed, there is little or no additional tax on the conversion if you act before the money grows much.

The cleaner you keep the timing and paperwork, the simpler the outcome. Many people convert shortly after contributing so there are minimal earnings to tax. You report the nondeductible contribution and the conversion on Form 8606, which establishes that you already paid tax on the basis and prevents being taxed twice.

• Step 1: Contribute to a traditional IRA (nondeductible because of your income).
• Step 2: Convert the traditional IRA to a Roth IRA.
• Step 3: File Form 8606 to report the nondeductible basis and the conversion.
• Step 4: Invest the Roth dollars in low-cost ETFs and let them compound tax-free.

The Pro-Rata Rule: The One Thing That Breaks It

The backdoor Roth is clean only if you have no other pre-tax money in any traditional, SEP, or SIMPLE IRA. The pro-rata rule treats all your traditional IRA balances as one pool, so a conversion is a proportional blend of pre-tax and after-tax dollars. If you have a large pre-tax IRA, much of your conversion becomes taxable even though your new contribution was after-tax.

Suppose you have a sizable rollover IRA from an old 401(k). When you convert your fresh nondeductible contribution, the IRS counts it as a slice of the whole pool, and most of the converted amount is taxed. A common fix is to roll the pre-tax IRA into your current employer's 401(k) first, if the plan accepts it, which empties the IRA pool and leaves only your after-tax contribution to convert cleanly.

Once the Money Is in the Roth

After the conversion lands, you have ordinary Roth IRA money that grows tax-free with no required distributions for you. From here it behaves like any Roth, so the natural move is to invest it in simple, low-cost funds such as VOO or VTI and leave it alone to compound.

The backdoor is something many high earners repeat every year, and some pair it with the mega backdoor Roth through their 401(k) to move far larger sums. Because the pro-rata rule and the paperwork can trip people up, it is worth confirming your specific situation with a tax professional before making it an annual habit.