Glossary term

Form 8606 - Nondeductible IRAs

Form 8606 reports nondeductible IRA contributions and helps track basis and taxable amounts for certain IRA distributions and conversions.

Updated

May 22, 2026

Read time

2 min read

What Is Form 8606?

Form 8606, Nondeductible IRAs, is an IRS form used to report nondeductible contributions to traditional IRAs and to calculate taxable and nontaxable portions of certain IRA distributions. It is also used for Roth IRA conversions and some Roth IRA distributions.

The form is especially important because it tracks IRA basis. Basis represents after-tax money in an IRA. Without proper basis tracking, a taxpayer may pay tax twice on money that was already taxed.

Key Takeaways

  • Form 8606 reports nondeductible traditional IRA contributions.
  • It helps track after-tax basis in traditional IRAs.
  • It is used for certain Roth conversions and Roth IRA distributions.
  • Basis tracking can affect taxable IRA withdrawals for many years.
  • Taxpayers should keep copies of Form 8606 with long-term tax records.

How Form 8606 Works

A taxpayer files Form 8606 when making nondeductible traditional IRA contributions, taking distributions from traditional, SEP, or SIMPLE IRAs when basis exists, converting traditional IRA amounts to Roth IRA, or taking certain Roth IRA distributions.

The form applies a pro rata calculation when a taxpayer has both pre-tax and after-tax amounts in traditional IRAs. This means a distribution or conversion generally cannot be treated as coming only from after-tax dollars when pre-tax IRA money also exists.

Form 8606 is often relevant in backdoor Roth IRA strategies, where a taxpayer makes a nondeductible traditional IRA contribution and later converts it to a Roth IRA. The tax result depends on the taxpayer's total IRA balances and basis.

Common Form 8606 Situations

Situation

Why Form 8606 matters

Common caution

Nondeductible IRA contribution

Reports after-tax basis

Keep the form permanently

Roth conversion

Calculates taxable amount

Pro rata rule may apply

IRA distribution with basis

Separates taxable and nontaxable portions

All traditional IRAs are aggregated

Roth IRA distribution

May report basis and ordering rules

Depends on timing and distribution type

Limits and Misunderstandings

Form 8606 is not only for high-income taxpayers. Any taxpayer with nondeductible traditional IRA contributions or relevant IRA basis issues may need it.

It also is not optional recordkeeping when required. Missing forms can make it harder to prove basis years later, especially after account transfers, rollovers, or changes in tax preparers.

This entry is educational, not tax advice. IRA taxation depends on account type, contribution history, conversions, distributions, age, basis, and current IRS rules.

The Bottom Line

Form 8606 protects the tax record for after-tax IRA money. It is a small form with long-term consequences because it can determine how much of future IRA distributions or conversions is taxable.

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