Liz Weston

Dear Liz: You recently advised a reader that if their income was too high to contribute to a Roth IRA, they could still contribute to an IRA or any after-tax options in their 401(k). You didn’t mention a two-step Roth IRA — first making a nondeductible contribution to an IRA and then immediately converting that amount to a Roth. That way those people whose income is too high to contribute to a direct Roth IRA can still have a Roth IRA using the two-step process.

Answer: This is known as a backdoor Roth contribution, which takes advantage of the fact that the income limits that apply to Roth contributions don’t apply to Roth conversions. Conversions, however, typically incur tax bills and don’t make sense for everyone. If you have a substantial amount of pretax money in IRAs, the tax bill can be considerable. (The tax bill is figured using all your IRAs, by the way. You can’t get around it just by contributing to a separate IRA that you then convert.)

Incurring that tax bill could make sense if you expect to be in the same tax bracket in retirement, or in a higher one. If you’re young and a good saver, it’s a good bet that will be the case. Roth conversions also can be advisable later in life if your tax bracket could jump when you reach age 72 and have to start taking required minimum distributions from your retirement accounts.

If you expect to be in a lower tax bracket in retirement, however, you probably should forgo Roth conversions because you’ll pay more now in taxes than you would later.

Of course, if you have little or no pretax money in your IRA, then backdoor conversions get a lot more attractive because the tax bill would be minimal. Otherwise, you should seek out a Roth conversion calculator to get a better idea of whether a conversion might be the right choice.