Backdoor Roth Pro Rata Rule Calculator
What is the IRA Pro Rata Rule?
The Pro Rata Rule is an IRS regulation that determines the taxation of a Roth IRA conversion when an individual holds both pre-tax and after-tax (non-deductible) funds in their Traditional IRA accounts. The IRS views all your Traditional, SEP, and SIMPLE IRAs as one giant "bucket." You cannot simply choose to convert only the after-tax money; you must convert a proportional amount of everything in that bucket.
How the Calculation Works
To calculate the non-taxable percentage of your conversion, the formula is:
(Total Non-deductible Basis) / (Total Value of all IRAs) = Tax-Free Percentage
Total value includes all your IRAs (excluding Roth) as of December 31st of the year you do the conversion. This includes any gains your non-deductible contribution made before the conversion.
Example Scenario
Suppose you contribute $7,000 as a non-deductible contribution to a Traditional IRA. However, you already have a rollover IRA from a previous employer worth $93,000. Your total IRA balance is $100,000.
- Non-deductible basis: $7,000
- Total Balance: $100,000
- Tax-free ratio: 7% ($7k / $100k)
If you convert $7,000 to a Roth IRA, only 7% ($490) is tax-free. The remaining $6,510 is considered taxable income, even though you "just put the money in."
How to Avoid the Pro Rata Rule
The most common way to bypass this rule is a "Reverse Rollover." If your current 401(k) or 403(b) plan allows it, you can roll your pre-tax IRA funds into your employer plan. Since employer-sponsored plans are not counted in the pro rata calculation, this leaves only your non-deductible basis in the IRA, allowing for a 100% tax-free backdoor Roth conversion.