Why this matters: To get a more accurate estimate of the conversion taxes you'd have to pay, you'll need to enter the total amount of your non-Roth IRA retirement accounts—not just the value you're considering converting. Here's why:

Let's say you have a total of $60,000 in IRA savings. $20,000 of that is in after-tax contributions (also known as nondeductible or post-tax contributions) and the remaining $40,000 is in pre-tax (or deductible) contributions and earnings.

If you're considering converting just a portion of your IRA savings, you might ask if you could convert only the $20,000 of after-tax contributions, since you've already paid income taxes on them, and therefore only have to pay taxes on the investment earnings within that $20,000 and not the contributions themselves.

The answer is that you can't choose which of your IRA funds get converted. Instead, you'll need to consider all of your non-Roth IRAs together and pay a proportional share—this is known as the IRS Aggregation Rule. Whether you convert the entire $60,000 or a portion of it, you'll pay taxes based on your overall percentage of taxable funds, or 66% in this example.

Additionally, keep in mind that accounts held by a partner/spouse are considered separately, even if you file jointly, so don't include those amounts in your answer.

For more information, you can review your IRS Form 8606—which includes a record of your after-tax contributions each year—or check with your tax advisor.

Why this matters: If you've made nondeductible IRA contributions, you've already paid income taxes on them and won't be required to pay taxes again if you convert to a Roth. If you're uncertain whether you've made nondeductible contributions to an IRA, check your income tax records for IRS Form 8606.

When investors can't qualify for tax-deductible contributions to a Traditional IRA because of income or contribution limits, they may decide to make an IRA contribution with after-tax funds. If you've made nondeductible contributions to an IRA, you should have filed IRS Form 8606. If you have this form on file, select "Yes" and enter the total amount of nondeductible contributions. If you haven't filed this form, select "No." For more information, refer to IRS Publication 590 or check with your tax advisor.

Why this matters: Your filing status is a key factor in determining the amount of conversion taxes that will be due.

The income ranges that are associated with your tax rate are different, depending on your filing status. As a result, your filing status will directly affect the amount of taxes that will be due, should you choose to convert.

Why this matters: A partial conversion may help you avoid a higher income tax bracket for the year you convert, lower your conversion costs, and help you manage your potential tax consequences as you plan for retirement.

Converting your Traditional IRA to a Roth IRA doesn't have to be an all-or-nothing decision, and you can phase your conversions over time. Here are three important reasons to consider a partial conversion:

1. Avoiding higher income taxes in the current tax year: If you're near the top of your income tax bracket, converting a large amount from your Traditional IRA could push you into a higher tax bracket and increase your income tax bill. A partial conversion may help you avoid this.
2. Lowering your conversion costs: If you don't have enough cash available outside of your retirement funds to pay for the taxes on a full conversion, a partial conversion could be a viable alternative. It may make sense to figure out how much conversion tax you can pay without dipping into your IRA assets, and then figure out how much you can convert for that amount of tax.
3. Tax-risk diversification: Today's income tax rates are near historical lows, and much speculation is occurring regarding whether income taxes are expected to rise. Diversifying your income tax risk can help with your plans to protect your savings, no matter what may happen with income tax rates in the future, because you are splitting your tax payment across current and future tax rates. By converting some or all of your Traditional IRA funds to a Roth IRA, you are paying taxes now in order to reduce your taxable income in the future.

Tax risk diversification can be a comprehensive strategy that incorporates more than IRA investments. Diversifying the tax consequences of your assets as part of your retirement strategy includes considering dividing your assets among three account types: taxable accounts (such as a brokerage account), tax-deferred accounts (such as a Traditional IRA or 401(k)), and tax-free accounts (such as a Roth IRA).

Why this matters: Your marginal federal tax rate is calculated using your taxable income that is subject to ordinary income tax—not your gross income—and your income tax rate is an important factor in determining whether a Roth IRA conversion is right for you.

Your taxable income is your gross income after taking out any allowable deductions (above-the-line adjustments for such things as alimony, student loan interest, deductible IRA contributions, etc., as well as the standard or itemized deductions and personal exemptions). Taxable income isn't limited to what you earn on the job—other types of income, including interest income and distributions from pension plans count, too.

You can find your taxable income as a line item on your most recent completed federal income tax return. However, this figure could include different kinds of income—the tax rate on which could vary. Depending on how much of your income is from qualified dividends and long-term gains, you can use the income tax return line item directly or adjust it. If you choose to adjust it, subtract your qualified dividend and long-term gain income from the taxable income line item to get the amount that is subject to ordinary income tax.

If you don't have your federal income tax return handy, enter your best estimate. For more information about taxable income, refer to IRS Publication 590 for tax assistance resources.

Why this matters: Your federal income tax bracket determines how much income tax you'll pay this year, which is a key consideration in deciding whether a Roth IRA conversion makes financial sense for you.

Your federal income tax rate is the starting marginal percentage at which conversion assets will be taxed. The calculator automatically calculates an estimated income tax rate based on the taxable income you entered, not including any potential conversion income which could move you into a higher tax bracket for the year you convert. For the most accurate result, make sure you've correctly entered your taxable income that is subject to ordinary income tax.

The calculator does not consider the alternative minimum tax (AMT). As converted funds are taxable, it is possible that the conversion amount could make you subject to the AMT. Be sure to consult your tax advisor.

Why this matters: A Traditional IRA can offer you tax benefits now, but a Roth IRA can give you more control over income taxes if you think you'll be taxed at a higher rate in retirement.

For this reason, your future income tax rate will have a significant effect on your calculator result. This calculator can help you estimate if the tax-free growth benefits of a Roth IRA will outweigh the effects of your tax rate in retirement being lower than your current tax rate.

Based on the information you provided, this calculator enters your current federal income tax rate for your future tax rate, but you may wish to adjust this figure. It's true that you can't know for sure what your federal income tax rate will be in the future, so estimating can be a bit of a challenge.

Your future income will determine your future tax bracket, which will determine the rate at which you will be taxed in the future. It's also important to consider that future tax laws may change over time, and they will be a critical factor in your future tax rate.

One approach to estimating your future tax rate is to base your future income tax rate on the amount you think you'll need to live on for your first year of retirement. Ask yourself how that amount compares to what you're making now—is it less, more, or about the same?

Here are some important additional considerations:

1. Today's income tax rates are near historical lows, and much speculation is occurring regarding when income taxes can be expected to change
2. If you will no longer be making mortgage or college tuition payments in retirement, that will directly affect your ability to lower your taxable income through deductions
3. You may have multiple income streams—think through the possibilities and consider your possible total combined income

If you think your income at the time of retirement will be higher than your current income, then you would likely want to consider protecting yourself from tax consequences resulting from being in a higher income tax bracket (and, therefore, being taxed at a higher rate) than you are now. In this case, a Roth IRA could be a smart way to help gain more control over tax consequences when you need to begin taking withdrawals from your retirement account. If you have questions, refer to IRS Publication 590 for tax assistance resources.

Please note that if your primary reason for converting to a Roth IRA is estate planning, consider inputting your current tax rate for this question.

Why this matters: State tax rates may be as high as 13.3%, so inputting your state taxes in your calculation is an important factor in getting a more accurate result. It's important to note, however, that some states treat the IRA conversion amount differently—not all consider it as taxable income—so be sure to check with your tax advisor.

Current state individual income tax rates range from 0% - 13.3%. For additional information on current state income tax rates, you can:

• Visit the official website for your state government
• Review your past state income tax returns
• Contact your tax advisor
• Refer to IRS Publication 590 for information on tax assistance resources

As with federal income taxes, speculation is occurring regarding whether state income taxes are expected to change. Consider your current state income tax rate and enter your best estimate. Relocating to a different state in retirement can have a significant effect on your state tax rate. For additional information, you can:

• Visit the official website for your state government
• Review your past state income tax returns
• Contact your tax advisor
• Refer to IRS Publication 590 for information on tax assistance resources

Why this matters: It's important to remember that the amount you convert must be held in your Roth IRA for at least five years or until you turn the age of 59½, or you could incur a 10% early withdrawal penalty.

Additionally, the longer you leave your assets in your IRA without withdrawing them, the more time you have for potential tax-free growth.

If estate planning is a goal of your Roth IRA conversion, consider that, although you may not need to make withdrawals during your lifetime, withdrawals will be required when your heirs inherit the account.

This calculator does not take the early withdrawal penalty into consideration, so please make sure you enter the correct number, or contact your tax advisor.

Upon first review of the bar chart, conversion might not look like it makes sense but you may want to consider assessing a few more variables before making a decision:

If the hypothetical value of your unconverted IRA is greater than your hypothetical Roth IRA value, check the section labeled "Impact on Current Tax Rate":

• If converting pushes you into a higher tax bracket...

Adjust the amount you would like to convert (using either a percentage or a dollar figure) until you find an amount that does not push you into a higher tax bracket and then review the bar chart to see which type of account has the greater proposed value. In many cases, a conversion can still make sense it just depends on the amount of funds selected:

• If converting does not push you into a higher tax bracket...

A conversion probably does not make sense at this time.

Additionally, if the estimated conversion taxes are too high (shown in the section labeled "Managing Taxes Due"), you can adjust the Partial Conversion Amount until you find a conversion tax amount that you can afford.

If the total taxes you owe upon conversion are more than you can afford to pay from sources other than your IRA, consider partial conversions over multiple years. Roth conversions can be done every year regardless of income level or filing status, so if a conversion is right for you and the only barrier is the tax payment, investors can achieve an optimal conversion amount through multiple conversions over a several-year period. You can choose to convert any amount, so choose an amount that will generate a tax payment you can afford and tolerate.

Why this matters: Your comfort with risk and the subsequent rate of return from your investment decisions will influence how quickly your investment earnings can make up for any taxes you'll be required to pay if you convert.

Based on your risk tolerance, as well as your asset allocations and expectations for future market performance, select an estimated average rate of return for your investments from now until retirement. The options provided in the drop-down box include estimated average annual returns by risk profile. For details, see "Average Rate of Return" under Calculator Assumptions.