Form 8606
Form 8606: Nondeductible IRAs and Roth Conversions
The federal form tracking after-tax (nondeductible) contributions to traditional IRAs and Roth conversions, essential for backdoor Roth IRA strategies and pro-rata calculations.
Who Files Form 8606
Anyone making nondeductible traditional IRA contributions (typically due to income limits on deductibility), executing Roth conversions, or taking distributions from a traditional IRA with a basis. Required for backdoor Roth strategy users to track basis across years.
What Form 8606 Reports
Part I tracks nondeductible contributions and basis. Part II reports Roth conversions and the taxable portion under the pro-rata rule. Part III reports distributions from a traditional IRA where basis exists. Failing to file Form 8606 in a year of nondeductible contribution loses the basis and converts later distributions back into fully taxable. The IRS allows late filing of missed Form 8606s with a $50 penalty per year, often waived for reasonable cause.
Key Deadlines
- Filed with Form 1040 by April 15 each year
- Missing years can be filed late with reasonable-cause penalty waiver
Common Mistakes
- Skipping Form 8606 in a backdoor Roth year and losing basis tracking
- Forgetting the pro-rata rule when other pre-tax IRA balances exist (SEP, SIMPLE, traditional)
- Confusing Form 8606 (IRA basis) with Form 5498 (custodian-issued contribution report)
- Filing Form 8606 in a year when no nondeductible contribution or conversion occurred
Best Practices
- File Form 8606 EVERY year you make a nondeductible IRA contribution, even if you do not convert. Skipping a year loses the basis tracking.
- For backdoor Roth strategy, watch the pro-rata rule against ALL pre-tax IRA balances (Traditional, SEP, SIMPLE). Roll pre-tax IRAs into a 401(k) BEFORE converting to clean the math.
- File missing prior-year Form 8606s late under the reasonable cause framework. The $50 per year penalty is routinely waived.
- Reconcile Form 8606 against Form 5498 (custodian-issued contribution report). Discrepancies usually mean a missed nondeductible contribution.
- For Roth conversions, time them in low-income years (pre-Social Security retirement, sabbatical, business loss year) to maximize after-tax efficiency.
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Related Tax Terms
Backdoor Roth IRA
A two-step strategy of contributing to a non-deductible traditional IRA and converting it to Roth, used by high-income earners who exceed direct Roth IRA contribution limits.
Required Minimum Distribution (RMD)
The annual minimum amount that must be withdrawn from most retirement accounts after a specified age, taxed as ordinary income.
SEP-IRA
A simplified employee pension IRA allowing self-employed individuals and small business owners to contribute up to 25 percent of net earnings to a traditional IRA structure.
Solo 401(k)
A retirement plan for self-employed individuals and small business owners with no full-time employees, allowing both employee deferral and employer profit-sharing contributions.
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