Some Americans earn too much to contribute directly to a Roth IRA. A strategy commonly called the backdoor Roth IRA can provide another route: make a nondeductible contribution to a traditional IRA and then convert that money to a Roth IRA.
The process is permitted under federal tax rules, but it is not automatically tax-free. A rule involving all of an investor’s traditional IRA money can create an unexpected tax bill.
How the Strategy Generally Works
An eligible investor contributes after-tax money to a traditional IRA. Because the contribution is nondeductible, it does not create an income-tax deduction. The investor then converts the traditional IRA funds into a Roth IRA.
The conversion is reported for tax purposes. If the investor converts only after-tax contributions and has no other relevant pre-tax IRA balances, the taxable portion may be small, although investment earnings before conversion can be taxable.
The strategy is not a special account created by the IRS. It is a sequence of transactions involving existing IRA rules.
The Pro-Rata Rule
The most important complication is the pro-rata rule. The IRS generally does not allow an investor to treat a conversion as coming only from the after-tax dollars in one particular traditional IRA while ignoring other pre-tax traditional IRA money.
Instead, the tax calculation considers the investor's combined balances in traditional, SEP and SIMPLE IRAs, along with distributions and conversions during the year. This can make part of a conversion taxable even when the investor carefully contributed after-tax money.
For example, imagine someone makes a $7,500 nondeductible IRA contribution but already has a substantial pre-tax traditional IRA balance from an old workplace retirement plan. The conversion may include a taxable portion because the IRS calculation takes the broader IRA picture into account.
The exact result depends on the balances and transactions involved.
Why Form 8606 Matters
Form 8606 is used to report nondeductible IRA contributions, certain IRA distributions and Roth conversions. It helps track the investor's after-tax basis so that the same money is not taxed twice.
Failing to file the form when required can create problems years later. An investor may struggle to demonstrate which portion of an IRA distribution or conversion represents previously taxed contributions.
The IRS instructions explain when Form 8606 is required and how basis is calculated. Investors should keep copies of filed forms and relevant account records.
Timing and Investment Gains
The time between making a nondeductible contribution and completing a conversion can matter. If the account earns interest or investment gains before the conversion, those gains may be taxable when converted.
There is no guarantee that a conversion will be tax-free simply because the original contribution was made with after-tax dollars. The investor must account for earnings and other IRA balances.
A Strategy That Requires a Full Account Review
Before using a backdoor Roth approach, investors should identify every traditional, SEP and SIMPLE IRA they own, including accounts that may have been opened years earlier. They should also review whether an eligible employer plan accepts rollovers from traditional IRAs. In some circumstances, moving eligible pre-tax IRA money into a workplace plan may affect the calculation, but plan rules and tax consequences need careful review.
The strategy can be useful, but a transaction that looks simple on a brokerage website may have complicated tax consequences.
The Bottom Line
A backdoor Roth IRA can help some investors fund a Roth account when direct contributions are restricted by income. The pro-rata rule, taxable conversion amounts and Form 8606 reporting are essential parts of the process. Investors should calculate the tax impact before converting money rather than assuming every conversion is tax-free.
