IRS Tax Forms · Tax Year 2025
Form 8606 Instructions: Nondeductible IRAs and Backdoor Roth Reporting
Form 8606, Nondeductible IRAs, reports nondeductible traditional IRA contributions, calculates the taxable portion of certain IRA distributions and Roth conversions, and reports certain Roth IRA distributions. It also preserves after-tax IRA basis so properly reported money is not taxed twice. This guide covers the 2025 form filed in 2026.
Official sources
Official IRS Form 8606 Resources
IRA basis, conversion, and distribution treatment depends on the taxpayer's complete transaction history. Use the official instructions and obtain qualified tax advice for a specific return.
Quick reference
Form 8606 at a Glance
Question; Quick answer
- What is Form 8606 used for?
- Reporting nondeductible traditional IRA contributions, basis-related distributions, Roth conversions, and certain Roth IRA distributions.
- Is it the backdoor Roth tax form?
- It is the main reporting form for many backdoor Roth transactions, although “backdoor Roth” is not an official account or form name.
- What is IRA basis?
- Generally, after-tax IRA money that should not be taxed again when accurately tracked and recovered.
- Does a conversion automatically remain tax free?
- No. Pre-tax IRA money, earnings, and the pro rata rule can create taxable income.
- Do spouses share one Form 8606?
- No. Each spouse files a separate form when required, even on a joint return.
- Can Form 8606 be filed alone?
- Yes, when the taxpayer has no return-filing requirement but must file Form 8606. The standalone form must be signed.
Key points
Key Takeaways
- A traditional IRA contribution and a Roth conversion are separate events that may fall in different tax years.
- The pro rata rule generally combines all traditional, traditional SEP, and traditional SIMPLE IRAs owned by one taxpayer.
- Form 1099-R and Form 5498 provide transaction data but do not replace Form 8606.
- Line 6 uses required December 31 IRA values, not only the balance in the account that was converted.
- Line 14 carries unrecovered traditional IRA basis into future years.
- A regular Roth IRA contribution alone does not require Form 8606.
Form purpose
What Is Form 8606?
Form 8606 tracks and allocates after-tax basis in individual retirement arrangements. It prevents properly reported nondeductible contributions from being taxed again and calculates taxable income when pre-tax and after-tax IRA money is distributed or converted.
| Part | What it reports |
|---|---|
| Part I | Nondeductible traditional IRA contributions and distributions or conversions involving traditional IRA basis |
| Part II | Traditional IRA amounts converted to Roth IRAs and the taxable conversion amount |
| Part III | Roth IRA distributions that must be tested under the ordering and basis rules |
For this form, “traditional IRA” generally includes traditional SEP and traditional SIMPLE IRAs. “Roth IRA” generally includes Roth SEP and Roth SIMPLE IRAs. Employer SEP or SIMPLE contributions are not the taxpayer's nondeductible traditional IRA contributions.
What Is IRA Basis?
Traditional IRA basis generally includes nondeductible contributions and qualifying nontaxable amounts rolled into traditional IRAs, reduced by basis already recovered and adjusted for special rules. It belongs to the taxpayer's aggregated IRA pool, not one chosen account.
Traditional IRA basis in Part I is separate from regular Roth contribution basis and conversion or rollover basis used in Part III. Custodian statements do not necessarily show tax basis, so prior Forms 8606 and supporting records matter.
Deductible vs. Nondeductible IRA Contributions
A deductible and a nondeductible contribution can be made to the same traditional IRA, but their tax treatment differs. A deductible contribution is generally claimed on Schedule 1 and does not create basis. A nondeductible contribution is reported on Form 8606 and becomes basis. For 2025, combined regular contributions to traditional and Roth IRAs were generally limited to the smaller of taxable compensation or $7,000, increased to $8,000 at age 50 or older. Filing status, modified adjusted gross income, and workplace-plan coverage can restrict the deduction even when the contribution is allowed.
Filing requirements
Who Must File Form 8606?
File the 2025 form when an applicable reporting requirement below applies, including a timely contribution made in 2026 and designated for 2025.
| Situation | Form 8606 generally required? |
|---|---|
| Nondeductible contribution to a traditional IRA for 2025 | Yes |
| Conversion from a traditional IRA to a Roth IRA in 2025 | Yes |
| Traditional IRA distribution while traditional IRA basis existed | Yes, subject to exclusions in the instructions |
| Divorce or separation transfer that changed either spouse's traditional IRA basis | Yes |
| Nonqualified Roth IRA distribution reportable in Part III | Yes |
| Distribution from an inherited traditional IRA with basis or certain inherited Roth IRA distributions | Generally yes; separate forms may be required |
| Only a deductible traditional IRA contribution or regular Roth IRA contribution | Generally no for that reason alone |
Rollovers, qualified charitable distributions, HSA funding distributions, returned contributions, recharacterizations, and certain repayments have special treatment. Apply the instructions for the actual transaction.
Does a Backdoor Roth Require Form 8606?
A backdoor Roth commonly requires Form 8606 because the form reports the nondeductible contribution and conversion and calculates the taxable portion. A contribution made in early 2026 and designated for 2025 belongs on the 2025 form. A conversion completed in 2026 belongs on the 2026 return, so one strategy can affect two tax years.
Compare the forms
Form 8606 vs Forms 1099-R, 5498, and 5329
| Form | Main purpose |
|---|---|
| Form 8606 | Reports basis-related IRA activity and calculates taxable and nontaxable amounts |
| Form 1099-R | Custodian or payer report of an IRA or retirement-plan distribution |
| Form 5498 | Trustee report of IRA contributions, rollovers, conversions, and account information |
| Form 5329 | Calculates certain additional taxes, including excess IRA contributions and some early distributions |
A Form 1099-R can report a conversion even when little or none is taxable. Box 2a may not reflect the taxpayer's complete basis. Form 5498 often arrives after the filing deadline, so prepare from reliable contribution and custodian records and reconcile it later.
Before you start
What Records Do You Need?
Gather:
- Prior Forms 8606, especially the latest line 14
- December 31 statements for every traditional, SEP, and SIMPLE IRA
- Forms 1099-R and Forms 5498
- Contribution confirmations and records showing whether a deduction was claimed
- Rollover, recharacterization, returned-contribution, and repayment records
- Roth contribution, conversion, rollover, and distribution history when Part III applies
- Divorce or inherited-IRA records when relevant
Confirm both the contribution year and transaction date. Contributions may be designated for the preceding year through the normal deadline, but conversions are reported in the calendar year they occur.
Conversion calculation
Backdoor Roth IRA and the Pro Rata Rule
A backdoor Roth usually means making a nondeductible traditional IRA contribution and converting traditional IRA money to a Roth IRA. For many filers, Form 8606 is the Roth conversion tax form that reports this sequence. It does not guarantee a tax-free conversion.
When pre-tax and after-tax money coexist in traditional IRAs, the conversion generally contains a proportionate share of each. The taxpayer usually cannot select only after-tax dollars.
| Included in the 2025 calculation | Generally not combined in line 6 |
|---|---|
| December 31 value of all traditional IRAs, including traditional SEP and SIMPLE IRAs | A spouse's IRAs |
| Outstanding traditional IRA rollovers required by the instructions | A 401(k), 403(b), or other qualified employer plan still held in that plan |
| Applicable traditional IRA distributions and conversions during 2025 | Roth IRA balances |
| Required adjustments for certain 2025 repayments | Outstanding rollovers from a traditional IRA to a qualified employer plan |
The simplified relationship is:
Basis available for the year
÷ (year-end traditional IRA value + relevant distributions + conversions)
= nontaxable percentageThe form includes adjustments and rounding, so this is not a substitute for Form 8606. Include the conversion account's remaining December 31 balance with every other applicable IRA balance. A zero balance on conversion day is not enough if another included IRA holds pre-tax money on December 31.
A Roth conversion tax calculator needs prior basis, conversion and distribution amounts, all required December 31 IRA values, and special adjustments. Estimating the final tax also requires the complete federal and state return.
Form walkthrough
How to Fill Out Form 8606
Follow the form's skip instructions because not every filer completes every part.
Part I: Contributions, Distributions, and Basis
| Line or group | Purpose |
|---|---|
| Lines 1 and 2 | Enter 2025 nondeductible contributions and prior traditional IRA basis |
| Lines 3 through 5 | Combine basis and separate certain contributions made after year end |
| Line 6 | Enter all required December 31 traditional IRA values, add specified outstanding rollovers, and apply required repayment adjustments |
| Lines 7 and 8 | Enter applicable traditional IRA distributions and Roth conversions |
| Lines 9 through 13 | Calculate the nontaxable percentage and basis recovered |
| Line 14 | Carry remaining traditional IRA basis forward |
| Lines 15a through 15c | Calculate taxable and nontaxable traditional IRA distributions |
Line 1 includes only the nondeductible portion of 2025 traditional IRA contributions, not all IRA funding. Line 2 should generally reconcile to prior line 14, adjusted for intervening events. Reconstruct missing basis rather than entering zero automatically.
Part II: Roth Conversions
Line 16 reports the amount converted, line 17 reports basis allocated to it, and line 18 reports the taxable amount. Gross conversion amounts generally appear on Form 1040 line 4a and taxable amounts on line 4b. Earnings before conversion can create taxable income.
Part III: Roth IRA Distributions
Part III applies to Roth distributions not excluded by the instructions. The ordering rules generally treat regular contributions as distributed first, followed by conversion and rollover layers, then earnings. Lines 19 through 25 calculate the taxable amount. Form 5329 may separately apply to an additional tax.
The five-year test for a qualified Roth distribution and the tests for conversion layers are not identical. Review the distribution's full history.
Return reporting
How Form 8606 Flows to Form 1040
Form 8606 calculates taxable amounts but does not replace gross-distribution reporting.
| Result | 2025 return destination |
|---|---|
| Gross IRA distribution or conversion | Generally Form 1040, 1040-SR, or 1040-NR line 4a |
| Taxable traditional IRA distribution from line 15c | Generally line 4b |
| Taxable Roth conversion from line 18 | Generally line 4b |
| Taxable Roth IRA distribution from line 25c | Generally line 4b |
| Qualified disaster amount | Applicable Form 8915-F calculation and reporting |
| Additional tax on a distribution | Form 5329 and Schedule 2 when required |
Worked examples
Form 8606 Examples
Example 1: Contribution and Clean Conversion
A taxpayer under age 50 contributes $7,000 for 2025, claims no deduction, converts $7,000 in 2025, has no prior basis, and owns no other traditional, SEP, or SIMPLE IRA balance on December 31. Ignoring earnings:
Basis available: $7,000
Year-end included IRA value: $0
Conversion: $7,000
Nontaxable conversion: $7,000
Taxable conversion: $0
Remaining line 14 basis: $0Example 2: Conversion With Another IRA Balance
Assume the same contribution and conversion, but the taxpayer has $93,000 in other included IRAs on December 31:
$7,000 ÷ ($93,000 + $7,000) = 0.070
$7,000 × 0.070 = $490 nontaxable
$7,000 - $490 = $6,510 taxableApproximately $6,510 remains as basis for future years. This shows why the conversion account cannot be isolated from the taxpayer's other traditional IRAs.
Special situations
Special Form 8606 Situations
| Situation | Main review point |
|---|---|
| Recharacterized contribution | Treat an eligible contribution as made to the second IRA and attach the required statement. Conversions made in 2018 or later cannot be recharacterized. |
| Returned or excess contribution | Apply the separate return-of-contribution rules and consider Form 5329. |
| Divorce transfer | Both spouses generally file Form 8606 with an explanation when the transfer changes basis. |
| Inherited IRA | Maintain inherited basis separately; different decedents can require separate Forms 8606. |
Filing guidance
How and When to File Form 8606
Attach the 2025 Form 8606 to Form 1040, 1040-SR, or 1040-NR by the return due date, including extensions. For most calendar-year filers, the unextended deadline was April 15, 2026. An extension to file generally did not extend the time to pay.
If no income tax return is required but Form 8606 is required, complete and sign the standalone form and send it where the return would otherwise be filed. The 2025 IRA contribution deadline for most taxpayers was April 15, 2026; a 2025 conversion had to occur during calendar year 2025.
For a missing or incorrect form, use the revision for the affected year. Form 1040-X may be required if taxable income, a deduction, or another return item changes. Include the appropriate explanation, reconstruct basis from filed returns and custodian records, and carry corrected line 14 basis through every later affected year. Do not use a current-year form to repair an earlier year's record.
A required form omitted for a nondeductible contribution can trigger a $50 penalty, and overstated nondeductible contributions can trigger a $100 penalty, unless reasonable cause applies. The larger practical risk is losing basis and paying tax twice on the same after-tax money.
Review checklist
Common Form 8606 Mistakes
Omitting a traditional SEP or SIMPLE IRA from line 6
Combining spouses' IRA balances or basis
Reporting a contribution and conversion in the same year when their dates place them in different years
Treating Form 1099-R box 2a as the final taxable amount
Losing prior-year line 14 basis
Confusing a regular Roth contribution with a conversion
Ignoring earnings between contribution and conversion
Using one form for owned and inherited IRAs when separate treatment is required
Filing questions
Form 8606 Frequently Asked Questions
Is a backdoor Roth IRA legal?
Federal law permits nondeductible traditional IRA contributions and Roth conversions when their requirements are met. Accurate reporting and the pro rata rule still apply.
Is there an income limit for a Roth conversion?
There is no direct federal income limit on a Roth conversion. Income can affect contribution and deduction eligibility, and the conversion may be taxable.
Does a 401(k) affect the pro rata rule?
A balance still in a qualified employer plan is generally not on line 6. Pre-tax money rolled into a traditional IRA before year end can affect the calculation.
What if the contribution and conversion occur in different years?
Report the contribution for its designated tax year and the conversion for the calendar year in which it occurred. A 2025 contribution converted in 2026 can require a 2025 Form 8606 for the contribution and a 2026 form for the conversion.
How long should I keep Form 8606?
Keep Forms 8606 and basis support while basis remains and through the review period for the return reporting the final IRA distribution. That may be decades.
Mega Backdoor Roth vs Backdoor Roth: What Is the Difference?
A mega backdoor Roth generally uses after-tax employer-plan contributions and an in-plan conversion or Roth rollover. It is different from the nondeductible traditional IRA strategy commonly reported on Form 8606.
Where can I download Form 8606?
Download the tax-year-specific form and instructions from the official IRS links at the top of this page. Use the 2025 revision for 2025 contributions, conversions, and distributions, even when filing or correcting the form later.
How Can I Verify Form 8606 in Tax Software?
Inspect the generated form. Check lines 1, 2, 6, 8, 14, 15c, 18, and 25c against Forms 1099-R and 5498, custodian records, and prior Forms 8606. Software interviews and menus vary.
Related references
Related IRS Forms and Sources
Important information
Tax Information Disclaimer
This page provides general education, not individualized tax, legal, investment, or financial advice. Results depend on the taxpayer's complete IRA history and other facts. Review the official 2025 instructions and obtain qualified professional guidance before filing or acting on this information.
