After you file

I have a similar issue where I did not show my IRA basis for 2018 and my 2019 8606 just showed the non deductible IRA contribution for that year. Should I send the amended form 8606 for 2019? Do I have to enclose 1040-X? There is no change on my 1040 as a result of this change.

And my 2018 IRA was deductible and 2019 was non deductible. Does that change anything when i fill form 8606 in 2020 in which i converted my traditional IRAs (deductible and non deductible) to Roth IRA?

Thanks,

RG