If you are asking where do I report Roth IRA conversion on 1040, the answer is line 4a and line 4b: the full converted amount goes on line 4a, and the taxable portion from Form 8606 line 18 goes on line 4b. This guide covers the three-form sequence, the 2025+ box 7a renumbering, a worked pro-rata example, and the split-year Form 8606 trap.
You report a Roth IRA conversion on Form 1040 line 4a and line 4b. Enter the gross conversion (Form 1099-R box 1) on line 4a and the taxable amount from Form 8606 line 18 on line 4b. If line 18 is zero or less, leave line 4b blank while line 4a still shows the full gross.
Where do I report a Roth conversion on Form 1040?
Report a Roth conversion on Form 1040 line 4a and line 4b. Line 4a (IRA distributions) carries the gross amount converted, and line 4b (taxable amount) carries the figure from Form 8606 line 18, which is ordinary income for the year. There is no separate schedule; the conversion flows to line 4b through Form 8606, not directly from the 1099-R.
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A Roth conversion is treated as a distribution followed by a rollover, which is why it lands on Form 1040’s IRA-distribution lines 4a and 4b rather than a wage or pension line.
Which forms do I need: 1099-R, Form 8606, and Form 1040?
You need three forms in sequence: Form 1099-R (issued by your custodian, reporting the gross amount and distribution code), Form 8606 Part II (which computes the taxable amount on line 18), and Form 1040 lines 4a and 4b for the gross and taxable figures. Form 5498 also arrives but is informational only.
| Form | Who issues it | What it does |
|---|---|---|
| Form 1099-R | Custodian (January after the conversion year) | Reports gross amount in box 1, taxable amount in box 2a, distribution code in box 7a |
| Form 8606 Part II | You, with your return | Computes the taxable portion of the conversion on line 18 |
| Form 1040 | You | Line 4a shows the gross conversion; line 4b shows the taxable amount from Form 8606 line 18 |
| Form 5498 | Custodian (May) | Reports the Roth contribution created by the conversion; informational only, not filed |
There is no income limit on converting: unlike direct Roth contributions, which phase out at higher incomes, any taxpayer may convert regardless of MAGI. Sizing the conversion is covered in Q3’s guide on how much to convert to a Roth.
Do you have to report a conversion even if no tax is due?
Yes. A Roth conversion is a reportable distribution even when the taxable amount is $0, such as a clean backdoor Roth. You still file Form 8606 to document the basis and still enter the gross amount on Form 1040 line 4a. Skipping it loses the basis record and can cause the IRS to tax those dollars again.
What does the box 7a code on my 1099-R mean?
On 2025 and later Form 1099-R, the old box 7 was renumbered to boxes 7a through 7d, and box 7a now holds the distribution code. For a conversion, box 7a shows code 2 (early distribution, exception applies) if you were under age 59.5, or code 7 (normal) if you were 59.5 or older.
| Box 7a code | Meaning | When it applies |
|---|---|---|
| 2 | Early distribution, exception applies | Account owner under age 59.5 at the time of the conversion |
| 7 | Normal distribution | Account owner age 59.5 or older |
Code 2 signals the conversion exception, so the 10% early-distribution tax does not attach to the conversion itself. Box 2a is often unreliable in pro-rata cases, so Form 8606 does the authoritative math (Source: Instructions for Forms 1099-R and 5498, 2026).
How do I fill out Form 8606 Part II?
Form 8606 Part II is where the conversion is reported. Line 16 is the net amount converted, line 17 is the after-tax basis applied to it, and line 18 is line 16 minus line 17, the taxable amount that carries to Form 1040 line 4b. If line 17 is $0, line 18 equals the amount converted.
| Form 8606 line | Entry |
|---|---|
| Line 16 | Net amount converted to the Roth IRA during the year |
| Line 17 | Basis (after-tax amount) allocated to the conversion, from line 11 if Part I is completed |
| Line 18 | Taxable amount (line 16 minus line 17), carried to Form 1040 line 4b |
The IRS handoff rule is precise, and many guides get it wrong by implying line 4b should read “$0.” The instruction states: if your entry on line 18 is zero or less, do not include the result on Form 1040 line 4b, but do include the full distribution on line 4a (Source: Instructions for Form 8606, 2025). So line 4a always shows the gross conversion, while line 4b is blank when line 18 is zero or less.
How does the pro-rata rule change my taxable amount?
The pro-rata rule aggregates all of your traditional, SEP, and SIMPLE IRAs into one pool to decide how much of a conversion is taxable. The tax-free share equals your after-tax basis divided by the total year-end value of that pool; the rest is taxable. You cannot convert only the after-tax dollars, so a large pre-tax balance makes even a nondeductible contribution mostly taxable.
Consider a taxpayer with a $42,500 pre-tax rollover IRA who makes a $7,500 nondeductible contribution for 2026, then converts $7,500. Form 8606 works out as follows.
| Form 8606 line | Description | Amount |
|---|---|---|
| Line 1 | Nondeductible contribution for 2026 | $7,500 |
| Line 6 | Total value of all traditional/SEP/SIMPLE IRAs at 12/31/2026 | $42,500 |
| Line 8 | Net amount converted | $7,500 |
| Line 9 | Line 6 plus line 8 | $50,000 |
| Line 10 | Basis fraction ($7,500 ÷ $50,000) | 0.150 |
| Line 11 | Nontaxable portion of conversion ($7,500 × 0.150) | $1,125 |
| Line 16 | Amount converted | $7,500 |
| Line 17 | Basis applied (line 11) | $1,125 |
| Line 18 | Taxable amount | $6,375 |
Here $6,375 flows to Form 1040 line 4b and $7,500 to line 4a. Only 15% of the conversion escaped tax, even though the whole $7,500 was a nondeductible contribution, because the pre-tax balance dilutes the basis. This partial result surprises filers expecting $0.
How do I report a normal, fully taxable conversion?
When the money converted is entirely pre-tax, such as a deductible traditional IRA or a rolled-over 401(k), the whole conversion is taxable. With no after-tax basis, Form 8606 line 17 is $0 and line 18 equals the amount converted, and that full figure goes on both Form 1040 line 4a and line 4b as ordinary income.
For example, a $30,000 pre-tax conversion with no basis produces $30,000 on Form 8606 line 18 and on both Form 1040 line 4a and line 4b. Q3’s Roth conversion break-even analysis covers the crossover point.
How do I report a backdoor Roth conversion?
A backdoor Roth is reported in two steps on Form 8606: the nondeductible contribution goes in Part I (establishing basis), and the conversion goes in Part II. Because the contribution is nondeductible, Schedule 1 line 20 (the IRA deduction) stays blank. Each spouse files a separate Form 8606, and the pro-rata rule is applied per person, not per couple.
When the person doing the backdoor holds no other pre-tax IRA money, basis equals the conversion, so Part II line 18 is $0 and no tax is due. It stays clean only with no pre-tax IRA balance; otherwise the partial, mostly taxable pro-rata result applies.
How is the conversion taxed: ordinary income and the 10% penalty myth?
The taxable portion of a conversion is taxed as ordinary income at your marginal rate, not at capital-gains rates, and no 10% early-distribution penalty applies to the conversion itself, regardless of age. The myth is that converting before age 59.5 triggers the 10% tax; it does not. The income stacks on top of wages and pensions.
A separate trap catches early withdrawals. If someone under 59.5 withdraws converted amounts within the five-year period beginning January 1 of the conversion year, the 10% additional tax can be recaptured on the converted taxable amount, reported on Form 5329 Part I and Schedule 2 (Source: Instructions for Form 5329, 2025). Withholding taken from the conversion is itself treated as a distribution, reducing the amount reaching the Roth and interacting with that five-year clock.
Because it is ordinary income, a conversion can push other thresholds such as Medicare IRMAA (above $109,000 MAGI single and $218,000 joint, on a two-year lookback) and the net investment income tax. The conversion is not itself net investment income, but it can lift other income over the 3.8% NIIT threshold.
Which year do I report the conversion in?
You report a conversion in the year it is completed, not the year of any related contribution, so a conversion finished in 2026 belongs on the 2026 return. This creates the split-year Form 8606 trap: a nondeductible contribution made in early 2026 for 2025 sits on the 2025 Form 8606 Part I, while the 2026 conversion sits on the 2026 Part II.
Those two steps can land on different filing years, which routinely trips up software entry: miss the prior-year Part I and the current-year conversion looks fully taxable. A conversion made after December 31, 2017 also cannot be recharacterized (undone), so it is final (Source: Instructions for Form 8606, 2025). If you are instead reporting a plan-to-IRA rollover, see Q3’s guide on how to report a rollover on your taxes.
How do I enter a Roth conversion in TurboTax?
In TurboTax, enter a Roth conversion in two places, and entering only the 1099-R is the top reason the software overtaxes a backdoor Roth: record the nondeductible contribution under Deductions and Credits, then enter the 1099-R under Wages and Income and confirm on the follow-up screens that the money was converted.
- Under Deductions and Credits, the Traditional and Roth IRA Contributions topic records the nondeductible contribution, creating the Form 8606 basis.
- Under Wages and Income, the 1099-R topic captures the form as issued, including the box 7a code and the IRA/SEP/SIMPLE checkbox.
- Follow-up screens ask whether the money was converted to a Roth and request the year-end value of all traditional IRAs so the software can apply the pro-rata rule.
After entry, confirm Form 8606 line 18 reads $0 for a backdoor with no other IRA balances. The same two-step logic applies in FreeTaxUSA and TaxSlayer: enter the nondeductible contribution and the 1099-R, never just one.
What happens if I don’t file Form 8606 or don’t report it?
Failing to file a required Form 8606 carries a $50 penalty unless reasonable cause is shown, and overstating nondeductible contributions can carry a separate $100 penalty per overstatement (Source: 26 U.S.C. section 6693). The larger cost is lost basis: unreported after-tax dollars can be taxed again when later distributed, effectively double-taxing money you already paid tax on.
Form 8606 is filed with Form 1040 by the return due date, including extensions, and if basis was omitted a corrected or standalone Form 8606 can generally be filed for that year (Source: Instructions for Form 8606, 2025). Missing the income entirely is worse, because the custodian already reported the 1099-R to the IRS.
2026 IRA figures that frame the conversion
Contribution limits do not cap a conversion, but they frame the surrounding IRA rules and the standard deduction conversion income stacks against. For 2026, the IRA limit is $7,500 ($8,600 at age 50 and older), and the standard deduction is $16,100 single and $32,200 married filing jointly.
| 2026 item | Amount | Source |
|---|---|---|
| IRA contribution limit (under 50) | $7,500 | IRS Notice 2025-67 |
| IRA contribution limit (50 and older) | $8,600 | IRS Notice 2025-67 |
| Standard deduction, single | $16,100 | Rev. Proc. 2025-32 |
| Standard deduction, married filing jointly | $32,200 | Rev. Proc. 2025-32 |
| Standard deduction, head of household | $24,150 | Rev. Proc. 2025-32 |
You cannot convert an RMD, and a conversion must be completed by December 31 to count for that year. Q3 maintains related references on required minimum distributions for 2026 and the 2026 Roth conversion deadline.
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Frequently asked questions
Where do I report a Roth conversion on 1040?
Report a Roth conversion on Form 1040 line 4a (gross amount, from Form 1099-R box 1) and line 4b (taxable amount, from Form 8606 line 18). If line 18 is zero or less, leave line 4b blank while line 4a still shows the full distribution (Source: Instructions for Form 8606, 2025).
Do I have to report a Roth conversion on my taxes?
Yes. A conversion is a reportable distribution, so it appears on a Form 1099-R the custodian sends to you and the IRS, and it is reported on Form 8606 Part II with the taxable amount carried to Form 1040 line 4b. Reporting is required even when the taxable amount is $0, such as a clean backdoor Roth.
What form do I use to report a Roth conversion?
Three forms work together. Form 1099-R from the custodian reports the distribution, Form 8606 Part II calculates the taxable portion on line 18, and Form 1040 lines 4a and 4b record the gross and taxable amounts. Form 5498 is informational only and is not filed.
Do you get a 1099-R for a Roth conversion?
Yes. The custodian issues Form 1099-R for the conversion year, reporting the amount in boxes 1 and 2a and a code in box 7a: code 2 if you were under age 59.5, or code 7 if you were 59.5 or older. It is reportable even when done trustee-to-trustee.
Is a Roth conversion taxed as ordinary income?
Yes. The taxable portion is taxed as ordinary income at your marginal rate, not at capital-gains rates, and no 10% early-distribution penalty applies to the conversion itself, regardless of age. The income stacks on top of wages, pensions, and other ordinary income for the year.
How do I avoid paying taxes on a Roth conversion?
The taxable amount is fixed by basis, not by choice. Only after-tax basis reduces the taxable portion through the pro-rata rule on Form 8606, so a conversion of purely pre-tax money is fully taxable. A conversion of only nondeductible basis, with no other traditional IRAs, can produce a $0 taxable result on line 18.
What happens if I don’t report my Roth conversion?
Failing to file a required Form 8606 carries a $50 penalty absent reasonable cause, plus $100 per overstatement, and unreported basis can cause later distributions to be taxed as fully taxable (Source: 26 U.S.C. section 6693). Because the custodian already reported the 1099-R to the IRS, omitting the income can also trigger a notice and additional tax.
How do I report a backdoor Roth in TurboTax?
Enter it in two places: the nondeductible contribution under the IRA Contributions topic, which creates Form 8606 basis, and the Form 1099-R under the income section, where follow-up screens confirm it was converted to a Roth. Form 8606 line 18 then shows $0 for a backdoor with no other IRA balances.
This article is provided by Q3 Advisors for educational purposes only. It is not tax, legal, or investment advice. Tax rules change and depend on individual circumstances; figures and form references are current as of August 2026. Consult a qualified professional about your own situation. Q3 Advisors is a registered investment adviser; registration does not imply a certain level of skill or training, and additional information is available in our Form ADV.
