For an 1120S, you need to fill out forms:4562 Depreciation and Amortization - Where you will depreciate the property through the date is was destroyed. Any current year depreciation will flow onto line 14 on page one of the return. 4684 page 2 Casualty Theft and Losses - Where you will detail your loss. Make sure to recapture all depreciation. This amount will carry onto Schedule K1, (or divided on multiple K1s per shareholder percentages) line 10, with Code B to be reported on the shareholder's 1040. Note - there should be nothing from this transaction entered on form 4797 and nothing from this transaction should be entered on line 4 on page one of the return. Your software may have to be overridden to make this happen. Hope that helps!