Learn how the IRS aggregation rule calculates taxable vs non-taxable portions of Backdoor Roth conversions, and how to roll pre-tax assets into a 401(k) to avoid taxes.
The Backdoor Roth IRA is a staple wealth strategy for high-income earners. However, executing it without understanding the IRS Pro-Rata Rule (IRC Section 408(d)(2)) can trigger unexpected tax liabilities on Form 8606.
1. The IRS Aggregation Rule
The IRS does not allow you to cherry-pick non-deductible contributions for conversion. Instead, the IRS treats all of your Traditional, SEP, and SIMPLE IRA accounts as a single aggregated pool on December 31 of the conversion year. If 80% of your total IRA assets are pre-tax, 80% of your conversion will be taxable.
2. The Reverse Rollover Solution
To eliminate the pro-rata tax drag, investors can execute a "reverse rollover," transferring all existing pre-tax traditional IRA balances into an active employer 401(k) or 403(b). Employer plans are excluded from the pro-rata calculation, leaving only your non-deductible basis in the IRA for a 100% tax-free conversion.
Disclaimer: Confirm your employer plan accepts incoming traditional IRA rollovers before converting.