With respect to Form 2210 AI line 14 calculations, I ran some tests with a spreadsheet using the correct IRS worksheets and it appears that TT is incorrectly using the second period factor (2.4) instead of the correct factor of 4 for box (a) in their 2021 Form 2210 calculation. This appears to be a carryover of the 2020 calculation which combined income from the first two periods to assess underpayment penalties and would have used the column (b) factor. Line 14 Box (b) also appears to have used the wrong factor which also resulted in a significantly higher number in box 14 (b) than it should if the calculation was done correctly per the Pub 505 IRS worksheets. There may be other explanations for the bad numbers in line 14 (a)- (c), but since previous problems with 2021 Form 2210 line 10, box (a) were also the result of carrying over the 2020 Form 2210 calculation, it could be that line 14 is messed up in a similar way. To check if my spreadsheet was correctly implementing the IRS worksheet I went back to 2019 TT Form 2210 and compared what it calculated in line 14 to what my spreadsheet predicted for that year and they matched in all periods.
