For some odd reason, you need to make this election with TurboTax Business in Forms Mode (click the Forms icon in the upper right side of the screen).
Click the Open Form icon, expand the list of forms, scroll down, select S Corporation Elections Summary, and open that form. Place a couple of "X's" on Line 11 (the 1.263(a)-1(f) election), click inside the box to reveal the magnifying glass icon and then click the magnifying glass icon. Place a checkmark in the box on the Section 1.263-1(f) election form to make the election.
