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Level 2
January 26, 2026
Question

Rounding question on Form 8606

  • January 26, 2026
  • 1 reply
  • 78 views

On form 8606 (nondeductible IRAs) I have an amount of $1 on line 5 and 8. Because I also have a Rollover IRA with a balance much larger than $1 (line 6), the ratio on line 10 doesn't have a non-zero digit until the sixth digit after the decimal point, and Turbotax shows line 10 as "0.00000".
What is interesting, and this looks like a bug to me, is that line 11, which is supposed to be line 8 multiplied by line 10, shows $1.
Just reading the numbers shown in the resulting PDF, it looks like 1 * 0.00000 = 1, which is obviously wrong.
But even if Turbotax takes into account "behind the scene" the ratio beyond the 5th digit, the result should be rounded to $0. E.g. 1 * 0.0000063 = 0.0000063, which is closer to 0 than to 1. Why doesn't Turbotax round to the nearest whole number, i.e. $0?
I assume that such an error for $1 shouldn't trigger an audit, but it feels wrong that my conversion to Roth IRA is entirely nontaxable ($1 out of $1) in my return when in fact it should be taxable.

1 reply

fanfare
Level 15
January 26, 2026

Your Roth conversion is tax-free when the taxable portion of the conversion is less than 50 cents.

ZPPMAuthor
Level 2
January 26, 2026

That makes sense, as anything less than 0.5 would round to 0.

But in my case the non-taxable portion is less than 0.5, so I expect it to round to 0, and thus the taxable portion should be 1.

fanfare
Level 15
January 26, 2026

Form 8606 calculates the taxable portion of your distribution/conversion, not the non-taxable portion.

@ZPPM