Undoubtedly, the Roth IRA has some strong advantages over the traditional IRA. For example, the Roth IRA offers tax-free withdrawals of contributions and earnings upon the age of retirement, and the required minimum distribution (RMD) is not applicable. Fortunately, traditional IRAs can be converted to Roth IRAs.

At one point, there were restrictions on conversions. However, in 2010, Congress eliminated the $100,000 income limit on Roth IRA conversions. This allows traditional IRA owners in all tax brackets to convert their accounts. Basically, you can convert the traditional IRA contributions to a Roth IRA with one caveat; a portion of the amount converted is subject to income tax.

Conversions: The Basics

First, we'll quickly review the basics. Within certain income limitations (may change annually), taxpayers in lower tax brackets can receive an IRA contribution deduction on their federal tax returns for deposits made to Traditional IRAs. Taxpayers with incomes above IRS limits can still contribute to IRAs; however, they will not be entitled to an IRA deduction on their tax return. These non-deductible contributions form the cost basis in the account. Therefore, upon withdrawal, they are not taxed. Taxpayers with these contributions must file Form 8606 with the tax return.

(IRS Form 8606 is used to help determine the taxable portion of a distribution or conversion and must be filed in the distribution year.)

The Conversion Formula

When your traditional IRA balance consists of deductible and non-deductible contributions, any amount distributed or converted from the Traditional IRA is pro-rated to include a taxable and non-taxable portion of the assets.

You may figure the non-taxable amount by using the following formula:

Non-Taxable Amount=TDCTIB × DCwhere:TDC=Total deductible contributionTIB=Total IRA balanceD=DistributionC=Conversion amount\begin{aligned} &\textit{Non-Taxable Amount}=\dfrac{TDC}{TIB} \ \times\ \dfrac{D}{C}\\ &\textbf{where:}\\ &TDC = \text{Total deductible contribution}\\ &TIB = \text{Total IRA balance}\\ &D = \text{Distribution}\\ &C=\text{Conversion amount}\\ \end{aligned}Non-Taxable Amount=TIBTDC × CDwhere:TDC=Total deductible contributionTIB=Total IRA balanceD=DistributionC=Conversion amount

Let us say you have Traditional IRA non-deductible contributions of $8,000 that have grown to $100,000. The taxable amount would be:


Of the $8,000 that you convert, $7,360 would be taxable:

($8,000640=$7,360)(\$8,000 - 640 = \$7,360)($8,000640=$7,360)

This rule applies even if the deductible amounts and non-deductible amounts are held in separate Traditional IRAs. Also note that if you maintain multiple Traditional IRAs, their total balances must be combined in the formula above to determine the amount that can be excluded from income (i.e., the amount that is non-taxable).

A Conversion Example

What if all of your IRA savings are comprised of non-deductible IRA contributions? If so, then you can convert your entire non-deductible IRA to a Roth IRA, and you will only have to pay taxes on the earnings.

For example, Susan Smith is in a 30% tax bracket this year, and she only has one IRA worth $100,000. The IRA consists of $90,000 in non-deductible contributions and $10,000 in earnings. If she decides to convert the entire IRA to a Roth, she would only have to pay taxes on the earnings portion ($10,000). At a 30% tax rate, she would owe $3,000 in taxes to convert the entire $100,000 to a Roth.

If Smith had no earnings in this IRA, the entire $100,000 (all non-deductible contributions) could be converted with no tax liability. When earnings are present, the owner must consider if it would be more beneficial to pay the due taxes now, considering that the future benefit would be tax-free.

Where It Gets Tricky

When you have an IRA that contains normal contributions, non-deductible contributions, and earnings, the rules of conversions are more complex. It would be fantastic if you could simply single out the non-deductible contributions and only convert that portion to the Roth tax-free. However, IRS rules prevent this strategy. Let us take a look at the special tax treatment of partial conversions for owners with multiple IRA accounts or IRAs with both deductible and non-deductible contributions.

John Doe, a 30% taxpayer, has a traditional IRA worth $200,000 on Dec. 31, 2018, of which $100,000 is non-deductible contributions. Doe wants to convert $100,000 of this IRA to a Roth. Because Doe has $100,000 of non-deductible contributions in this Traditional IRA, you would think that he could convert the $100,000 of non-deductible contributions tax-free. Unfortunately, the IRS has a special formula that must be followed if you own an IRA with normal contributions.

Here's how it works:

Tax-Free Percentage=TND(YV+C)where:TND=Total non-deductible contributionsYV=Sum of year end value of all IRA accountsC=Conversion amount\begin{aligned} &\textit{Tax-Free Percentage}=\dfrac{TND}{(YV + C)}\\ &\textbf{where:}\\ &TND = \text{Total non-deductible contributions}\\ &YV = \text{Sum of year end value of all IRA accounts}\\ &C=\text{Conversion amount}\\ \end{aligned}Tax-Free Percentage=(YV+C)TNDwhere:TND=Total non-deductible contributionsYV=Sum of year end value of all IRA accountsC=Conversion amount

Thus, given the example above, John Doe would calculate the following:

$100,000 ÷ ($200,000 + $100,000)=$100,000 ÷ $300,000\begin{aligned} &\text{\$100,000}\ \div\ (\text{\$200,000}\ +\ \text{\$100,000})=\\ &\text{\$100,000}\ \div\ \text{\$300,000}\\ &\text{Tax-Free Amount of Conversion}\ = \ 33\% \ (\text{or }\text{\$33,333}) \end{aligned}$100,000 ÷ ($200,000 + $100,000)=$100,000 ÷ $300,000

Therefore, if John converts $100,000 to the Roth, he will have $33,333 ($100,000 x 33.3%) that is not-taxed and $66,667 ($100,000 x 66.7%) that will be taxed at his 30% tax rate.

The Bottom Line

The common misconception is that you can single out the non-deductible contributions and convert them specifically tax-free. Another misconception is that you simply divide the non-deductible contributions by the total value of the IRAs to determine the tax-exempt amount percentage. However, the formula is a little more complex. But now you know the rules, and doing the calculation correctly will keep the IRS off your back. Consult with your tax professional to ensure that the appropriate forms are filed and the calculations are accurate.