That field gets populated based solely on your inputs. When you enter your W-2 info, Turbotax has a block for you to check to assign the W-2 to either you or your spouse. Many people seem to blow by that or ignore it and end up assigning all W-2s to one person. When that happens, you have told turbotax that all of the income was for one person and turboax dutifully adds up all of the SS withholding, determines that it is more than the limit for one person, and puts the excess on Line 71. That is not a turbotax error, it is an error in your data input, and it is your responsibility to pay the penalties and interest.
