In 2021 tax return with 5329, I won't have the 2020 5329 excessive amount to base on and therefore , IRS requires me to amended 2020 tax return with the 2020 5329 to report the excess.
You said that the excess contribution for 2020 that will remain unresolved before the due date of your 2020 tax return. That's the amount that will be on line 24 of your 2020 Form 5329 when you file and the amount that will transfer to line 18 of your 2021 Form 5329. The 2020 Form 5329 will result in the $420 penalty being part of your tax liability from which your 2020 refund or balance due will be determined. There will be nothing to amend with regard to your 2020 tax return because you will already have reported the excess contribution and paid the additional $420 of tax.
