The pro-rata rule: the backdoor Roth IRA mistake that can create an unexpected tax bill
The backdoor Roth IRA strategy can trigger an unexpected tax bill if you overlook the pro-rata rule, which requires the IRS to treat all of your traditional IRA balances together when calculating how much of a conversion is taxable. A separate account, a prior 401(k) rollover, or even a year-end IRA balance you didn’t have at the time of conversion can all affect the result. Before contributing or converting, review your full IRA picture to avoid a costly surprise at tax time.
