Dear Liz: I’ve been researching the backdoor Roth IRA and I am finding some conflicting information regarding taxes owed on the conversions. I have two sizable rollover IRAs and one small ($1,600) traditional IRA. Can I make an after-tax contribution to the traditional IRA and convert that to a Roth and pay tax only on that IRA or do I have to consider all three IRAs?
Answer: Sorry, but you have to consider all three. The tax on your conversion will be based on the pre-tax portion of all your IRAs combined, not just the IRA where you make your contribution.
Backdoor Roths allow people to get money into a Roth when their incomes are too high to make a direct contribution. Instead, they contribute to a traditional IRA and convert that to a Roth because conversions don’t have income limits. Conversions require paying taxes proportionately on your pre-tax contributions and earnings, however, so the technique may not be advisable when you have sizable pre-tax IRAs that will trigger a large tax bill.