In 2020, I contribute to IRA $7K (which is $2K deductible and $5K nondeductible). In 2021, I convert the $5K IRA to Roth IRA. In 2022, I filed tax amendment of 2019. The $7K IRA deduction of 2019 became $7K IRA non deduction after the amendment. I didn't add $7K nondeductible of 2019 into my cost basis when I filed tax 2021. I have 2 questions:
1) Can I file tax amendment of 2021 and add $7K to cost basis or do I need to update form 8606 of tax 2020 first before I can file tax amendment of 2021?
2) Can I update form 8606 of tax 2020 without filing amendment?
Thanks.
