The pro-rata rule
The pro-rata rule states that any withdrawals you take from IRAs be equally divided between taxable and non-taxable funds. Under the pro-rata rule, ALL of your IRA holdings will affect the tax consequences of opening a Backdoor Roth.
For example, let’s say:
- You have $45,000 in a rollover IRA created from an old 401(k).
- Then you put $5,000 in a new nondeductible IRA.
- You have a ratio of 9:1 of taxable to non-taxable money.
- When you convert the $5,000 nondeductible IRA to a Roth, you will actually owe taxes of $4,500. That’s because 90% of your available IRA funds have never been taxed.
If you have a sizable existing IRA balance — be they traditional IRAs, rollover IRAs, or SEPs — this could create a large tax burden for the conversion year. One solution, if you can afford to pay the taxes, is to convert all of your IRAs to Roths at the same time.