TurboTax will guide you through an interview, where they will gather the information to file the loss on Schedule A.  You will have to enter the Fair Market Value (FMV) of the property before and after the event. This can sometimes but the most difficult part. Use a good faith estimate and keep records of how you came up with the values. The difference in FMV before and FMV after the event will be your reported casualty loss.

Here is an IRS guidance to estimating your loss. FAQs for Disaster Victims - Casualty Loss (Valuations and Sections 165 (i))  There is one method that allows you to use the repair cost to restore your property as your "loss". So the repair costs have to be the difference in the FMV before and after the event. So estimate your FMV before the event and subtract the repair costs to get the FMV after the event.

In TurboTax, jump to the entry area for casualty loss:

1. Open your return.
   (To do this, sign in to TurboTax and select the blue Take me to my return button.)
2. Search for "casualty loss" and then click the "Jump to" link in the search results.
3. On the Casualties and Thefts (or Stolen or Damaged Items) screen, select Yes.
4. Answer the interview questions describing your event.
5. When you complete the event and reach the Property Summary screen, you can enter any additional property losses by selecting the Add a Property butto