Published August 2026
What Form 8606 actually tracks
A backdoor Roth has two steps that each need to show up on Form 8606 in the year they happen: the nondeductible contribution to a traditional IRA (Part I), and the conversion of that money to a Roth IRA (Part II). If both happen in the same tax year — the common pattern — both parts get filled out on the same form for that year. The form’s real function is establishing and tracking your “basis” — the after-tax dollars in your traditional IRAs that shouldn’t be taxed again when converted or distributed.
The two parts that matter for a backdoor Roth
| Part | What it reports | Why it matters |
|---|---|---|
| Part I | This year’s nondeductible contribution, plus total basis carried forward from all prior years’ 8606 filings | Establishes the after-tax dollars the IRS shouldn’t tax again |
| Part II | The amount converted from traditional/SEP/SIMPLE IRA to Roth, and how much of it is taxable | Calculates the taxable portion using the pro-rata rule across all your traditional IRA balances |
Form structure and requirements per the IRS Instructions for Form 8606 (Nondeductible IRAs), current revision, and IRC §6693(b)(2) (failure-to-file penalty).
The mistake that causes real damage later
Part I of Form 8606 carries your running basis forward line by line, year after year, on line 14. If you skip filing it in a year you made a nondeductible contribution, the IRS has no record that money was already after-tax — and when you eventually convert or take a distribution, there’s no paper trail showing you shouldn’t be taxed on it again. The fix, if you’ve missed a year, is to file the late Form 8606 for that specific year (not just add it to this year’s filing) along with a reasonable-cause statement requesting the $50 penalty be waived; the IRS has generally been willing to waive it when the omission was a genuine oversight rather than an attempt to avoid reporting.
Frequently Asked Questions
Do I file Form 8606 every year I do a backdoor Roth?
Yes — every year you make a nondeductible contribution and/or convert traditional IRA funds to Roth, a new Form 8606 is required for that tax year.
What happens if I forget to file it?
You risk the IRS treating previously-taxed money as taxable again later, plus a possible $50 penalty per missed filing under IRC §6693(b)(2) — though this is typically waivable if you can show reasonable cause and correct it.
Does my tax software file Form 8606 automatically?
Most major software will generate it if you correctly answer the IRA contribution and conversion questions during filing — but it’s worth checking the actual form in your return, since a wrong answer earlier in the interview can cause it to be skipped.
Excellent video. Thank you!
Commenting to come back year-to-year
You didn't explain how line 8 gets carried to line 16 if it's $7,025.
So why would my 1099-R have the full Traditional IRA contribution amount on line 2a? i.e. all taxable. For where I made a Roth contribution, recharacterized it, then back doored it.
I had to pay about $2k for 2025 because I did a backdoor Roth. I sent my accountant my 1099R and he said that box 7 was supposed to have a g instead of a 2. I looked online and it seems like 2 should be okay for box 7. After watching this video, I filled out a 8606 manually and sent it to my accountant. I also told him about the 1040 changes as well. I'll hear what he says about this soon and hopefully he can get this stuff fixed.
Line #8 should be $7025 and line #10 should be x 0.9964. So that it matches line #16 and #17
Assuming $25 in your example is purely the interest that got credited during the period of holding the money in Trad IRA before converting it into ROTH IRA.
Great video. Accountant from Turbo Tax did all the mistakes you mentioned. 1040 4b showed same amount as 4a resulting in double taxation.
8606 Lines 1-14 were blank while Line 18 showed $7000 causing triple taxation for me!
I watched this video a couple of times and told them how and what to fix!
Please create a similar video for 8606 Lines 10 and 15 a, b and c for a use case where someone did backdoor Roth IRA in 2024 and in 2025.
Can you also show an example where contribution and conversion for 2025 id done 2026 for $7000 as an example. What should be the total basis in line 2? Especially when 2024 contribution and conversion happened in 2025. And also contribution and conversion happened on same day. So no additional gain.
Can you contribute non-deductible funds for 2025 in March 26 to a Traditional and then convert/backdoor to a Roth before April 15th? And would you submit that 8606 with your 2026 taxes or does it need to be with your 2025? With a side note that the 2025 taxes have already been filed?
Do I enter my 1099-R amount in line 6 of form 8606?
I am using TurboTax software. When my 8606 is generated, only box 1, 3 and 14 show my clean backdoor Roth conversion. Part II (box 16-18) are blank. Will the IRS reject my 8606?
My 1040 box 4b shows $0 and 4a shows my correct conversion $.
Thanks
If I contributed in 2026 for year 2025 will Fidelity generate 1099 this year or will I get this form in 2027?
Also if I already filed my taxes before the contribution, I just need to file an amendment with form 8606, correct?
I contributed part in 2025 and the other half in 2026… 1099-R only shows 2025 conversion. Do I include 2026 contribution on the form lines 4 and 14?
Hi thank you for the video. At 12:29 do I still need to file Form 8606 if I did not contribute towards the Back Door Roth IRA?
Thanks
First year Backdoor Roth, self filler for 1040. Question: Contributed 7,000 to Traditional IRA on 12/27/2025 waited for amount to clear then converted to roth-IRA on 01/07/2026. Fidelity did not send us a 1099-R for 2025. Filling out the 8606 do i still include the conversion to Roth? Or do i report that for the 2026 return?
For the 8606 is part 1, line 1 non deductible contributions is that generally the amount that was converted as shown i.e. 1099 R distributions?
I'm filing via Turbotax software online. So, I'll be e-filing. How do I attach Form 8606?
I saw your post to a comment about the Pennies and the Backdoor Roth IRA and the scenario matches my situation identically. I'm using tax software to complete my return and the software is rounding line 10 to 1.000, which is causing lines 11, 13, and 17 to match my contribution + gain ($7001) and I'm not showing a taxable amount of $1 in line 18 or 1040 4b. Is that okay?
If I made my contribution for 2025 between January 1, 2026 and April 15, 206 would line 4 be $7000? Then line 5 would be $0?
if i simply contributed 7000 in 2025 but not do a backdoor roth yet, is it just 7000 in line 1 and 3?
Quick question, If I contributed $7000 but my brokerage gave me a 1% match so it's $7070 and I converted it to Roth IRA. Does line 1 reflect 7000 or 7070 and if no, where should I put the 70$
Should the tax client receive a 1099 showing the amount made towards the contribution?
One more question, if turbo tax has been filing the 8606 wrong or not even triggering it, how does one rectify this? Can we amend the last tax return and add a corrected 8606 for every year turbo tax did it wrong.. possibly 6-7 years now.
Hi. Can you do a video on megaBD and BD, how should 8606 be filled out for each. For example, 7500 BD through trad Ira then to Roth and 27k in after tax money from 401k directly into Roth. And lastly what about 401k amount of 3000 rolled into traditional Ira, then rolled into Roth. I know the last scenario I pay taxes on it, so will 4b be 3k + any growth? Thanks