Form 2210 that many were waiting for has an error. Column B of Part IV, Section A is not supposed to be used if you are a calendar year filer but TurboTax is using it in lines 20 through 24 (but not 25-26). In cases that there is an overpayment in column A (line26), that is not picked up in column C line 20. Column C, in my case shows an underpayment when there should be an overpayment because of this error. Note - the 2210 Penalty Worksheet does pick up the overpayment from Column A, so the penalty calculation appears to be right, but the form submitted to IRS will show wrong numbers.
You are not alone! I have the same problem, and have not been able to figure out how to report an obvious programming error to TurboTax. It will be H&R Block for me next year since TurboTax seems to care so little about the quality of their product. Well, true confession -- I did not notice the error until after I filed, so it will be interesting to see if the IRS notices the error.
Unfortunately I talked to a support person on 3/2 in an attempt to get a status of the fix. They reported to me that they had no indication that it was a problem or that it was being worked on by programming staff. When I asked how to get it reported so it could be tracked, I was told that it was an IRS problem since they provide the forms and I'd have to report it to them. Since I didn't believe the answer I bought H&R Block software right after the call and the problem does not exist in their software.