To be able to claim any amount self-employed health insurance deduction with respect to your S corp, your W-2 from the S corp must have a nonzero amount in box 1. To be able to claim the full amount of premiums paid, the amount in box 1 of your W-2 from the S corp must be at least as much as the premiums paid. You need to have told TurboTax these amounts during entry of the Schedule K-1 (Form 1120S).
