You must have a copy of the original tax return you want to update.
The simplest way is to prepare your correct tax return (using TurboTax for example, or other means) and print it.
Then lay the paper printouts of both returns (correct and original) side-by-side.
You now have all the information needed to prepare Form1040X by hand.
It's pretty straight-forward.
The blank form in fillable PDF format and its instructions are available at www.irs.gov.
Mail to the same address you would mail your original tax
return.
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In this scenario, only Form 8606 is new or changed, and all of column B in 1040X should be zero, since you didn't take the deduction.
In Part III Explanation state
"here comes a changed Form 8606 since I never made the contribution".
