Note that in suggesting a possible tweak for problem with line 11 of Form 2210, I said that in lieu of entering the 2020 refund as a credit a person could enter it as a fifth estimated tax payment. It is easy to verify that only one of these entries is included by selecting the forms view and verifying in the Tax Payments Worksheet that the amount is only listed as a tax estimate (line 5, Federal) and that the block for carried over tax payments (line 6, Federal) is zero. Only one of these should show the refund credit amount.
In another forum someone commented that they were able to override Form 2210 line 11(a) to include the carried over tax refund credit that TT wasn't carrying forward from the tax payments worksheet. They didn't indicate if this override cause problems with IRS accepting e-filed return, which other overrides of Form 2210 and Form 2210AI lines have caused, but if the overriding Form 11 (a) to correct TT error is accepted by IRS, then that would be the preferred method in lieu of making the estimated payment tweak.
