How can I amend an IRS tax form 8606 (Nondeductible IRAs)? The form has a signature line, allowing it to be filed by itself, but I already filed one for the year in question and now need to amend it to make a correction. How can I do this? Do I just file another form 8606, or must I do a 1040-X? Do I also send this amended form 8606 to my state of California? Note that my 1040 remains unchanged with the update to the form 8606.
From the Instructions for Form 8606: