I've been facing the same issue for several years. The bottom line is that Turbo Tax won't fill out Form 8958 for you -- you have to do it yourself. I download the Form 8958 from the IRS and follow the instructions on the form. Then I add up the entries for all items except #11 (taxes withheld) to get the total for Columns B and C. Then in TurboTax, since my income is greater than my wife's, I calculate half the difference between us. I then use the Search Topics tab to search for 8958 and select it. On the earnings page that pops up I enter the amount just calculated (half the difference in earnings) on the earnings page as a subtraction adjustment for me and an addition adjustment for her. I then calculate half the difference between the withholding for me and my wife. (Assuming my withholdings are greater), in the withholding page I enter that amount as a subtraction adjustment for me and an addition adjustment for her. I do this on both my married filing separately form and my wife's married filing separately form. So far, the taxes filing separately have been greater than married filing jointly, so I've never filed this way (but I always check). I guess that if I really did file separately, Turbo Tax would somehow generate an 8958 form, but I've never gotten that far.
