Form 8606 Cost Basis

[YM23]

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.

[DanaB27]

Yes, if you filed a 2020 Form 8606 then this will need to be updated. You can file the 2020 Form 8606 alone if it won't change anything on your 2020 return. If it changes anything on your 2020 return then you will need to file a 2020 amended return.

Yes, you will need to amend your 2021 tax return.

[YM23]

Thank you very much for your help.