At the moment (until TurboTax fixes the glitch between the interview interface and the actual IRS forms for calculation of the underpayment penalty), the only way I know around this is to go to the Forms themselves and enter the data manually. Then the calculation seems to work (at least the answer changes and the penalty is lower--mine was cut by half.
So, go to the banner line at the top of the screen and select Forms. Then you will see a list of the IRS forms in the left-hand column of the page. Scroll down to Form 2210 (the Underpayment of Estimated Tax Form). If your experience is like mine, you will find that a lot of the form has already been filled in from information you entered in the Interview process. What wasn't filled in in my cases was Part II on the first page of the Form. I was surprised to see that box C ("Your income varied during the year and your penalty is reduced or eliminated when figured using the annualized income installment method...:" Check this Box. You will note at the end of this statement it tells you to go to Schedule A1 to Form 2210. Then either "Quick Zoom" (whatever that is) to Schedule A1 or just select that Schedule from the left hand column listing all the forms. Once you get to this form, you will again find that all the information you painfully calculated and entered in the Interview process, has not carried to the form. Enter this information in the appropriate places on the Schedule (I think the only information that you will have to enter are your annualized AGI (line 1) and annualizing your capital gains in the Capital Gain Computation Smart Worksheet. The rest of the information on the Form will be filled in for you. Toward the end of the Schedule (line 27) you will see the calculations which you need to carry over to Form 2210, Part III, line 10. I believe again you will find that once you have completed Schedule A1, most of the required information is already carried over to Form 2210. Again, this resulted in my calculated penalty being reduced by half.
