@kpf226
Since latest update of TT on 3/11/22 still doesn't fix any of the issues with Forms 2210 and 2210AI, TT may never fix the remaining problems including your issue with line 11. In lieu of including your 2020 refund as a tax payment credited to 2021 tax return, you could instead just include the amount of 2020 refund as a fifth estimated tax payment with the paid date being the date that your 2020 return was filed and/or accepted by IRS, which I assume was on or before 4/15/21. Looking at the tax payment worksheet in TT, this would result in the same total of estimated tax payments and refund credits for the year and should result in TT increasing line 11 (a) by the amount of your 2020 refund (via the fifth estimated payment tweak) which should eliminate the bogus underpayment penalty.
