Form 8906

[HOB2]

I did not make a non deductible contribution to an IRA.  Why is Turbo Tax generating form 8906?

[CatinaT1]

You've asked several questions about this, so I am aware you previously mentioned you have a Roth conversion.

A Roth conversion affects your Form 8606 even without a new contribution because the form isn't just a log of what you put in—it is a calculator.  When you move money from a Traditional IRA to a Roth IRA, that money is often a mix of "already taxed" dollars (your basis) and "never taxed" dollars (earnings and deductible contributions).

Since the IRS doesn't allow you to choose which dollars you convert, the form uses a specific mathematical flow to separate them.

Even if you didn't add a single penny of new after-tax money this year, the IRS requires you to recalculate your basis to ensure you aren't taxed twice on the money you converted.

Here is exactly how the conversion ripples through the form:

• The most important change happens at the bottom of Part I. Every time you convert money to a Roth, a piece of your historical basis (the "tax-free" part) is attached to that conversion.
• Line 2: You pull in your old basis (say, $5,000 from 2018).
• Line 13: This line calculates the portion of that $5,000 that was "used" to make your 2025 conversion tax-free.
• Line 14: It updates your total basis for the future. If you used $2,000 of your basis for this conversion, Line 14 will now show $3,000. That is your new starting number for 2026.

There is an additional calculation done on line 6-10. 

• Even if you have $10,000 of old basis and you only convert $10,000, you don't necessarily get a tax-free conversion.
• The conversion forces you to fill out Lines 6 through 10, where you list the value of ALL your Traditional IRAs.
• If you have $90,000 of pre-tax money elsewhere, the 8606 math will only allow a small fraction of your "old basis" to be applied to this conversion. The rest of your basis stays in the "bucket" for next year.

Part II (Lines 16-18):

• This is where the conversion actually happens on the form. Even with no new contributions:
• Line 16: Shows the total amount you moved to the Roth.
• Line 17: Pulls the nontaxable portion calculated in Part I (using your old basis).
• Line 18: This is the final result. It tells the IRS exactly how much of your conversion is taxable income on your 1040.

Think of Form 8606 as a mathematical filter. When you move money from a Traditional IRA to a Roth IRA, that money is often a mix of already taxed dollars (your basis) and never taxed dollars (earnings and deductible contributions). Without this update, the IRS would have no way of knowing:

• That a portion of the money you moved was already taxed (saving you money).
• How much of your "tax-free" balance is left for future years.
• That you followed the "Pro-Rata" law by looking at all your accounts instead of just one.