You didn't say whether you are using TurboTax Online or the desktop TurboTax software. If you are using the desktop software, you can go to forms mode, open Form 8960, click on the space for the amount on line 6, and enter an amount. This is one of the few things that you can enter directly on Form 8960. In TurboTax Online there is no way to make the entry, because there is no forms mode in TurboTax Online.
