Per IRS Instructions for Schedule A Itemized Deductions, on page A-12:
Complete and attach Form 4684 to figure the amount of your loss. Only enter the amount from Form 4684, line 18, on line 15.
On page A-13:
CAUTION! Don't enter a net qualified disaster loss from Form 4684, line 15, on line 15. Instead, enter that amount, if any, on line 16. See Line 16, later, for information about reporting a net qualified disaster loss.
You can only deduct personal casualty and theft losses attributable to a federally declared disaster to the extent that:
To review or modify these entries in your TaxAct® return:
TaxAct will use the higher of your Itemized Deductions or the Standard Deduction for your filing status to maximize the tax benefit to you. If you do not itemize deductions, you cannot take the casualty and theft deduction and Form 4684 Casualties and Thefts will not print with your return; however, you can print just that form to review the calculations if you wish.
If you have a casualty loss from a disaster that occurred in an area declared by the President to be a federal disaster area, refer to IRS Publication 547 Casualties, Disasters, and Thefts for more information. In the case of a federally declared disaster, an affected taxpayer can call 1-866-562-5227 to speak with an IRS specialist trained to handle disaster-related issues. For additional information, refer to the IRS.gov has the Latest Information for Taxpayers in Disaster Areas website.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.