In the wake of recent hurricanes, the IRS has issued a new Fact Sheet — FS-2017-11. It walks through the process of how to calculate Casualty and Disaster Tax Losses, as well as how to reconstruct records after a natural disaster, such as:

• Tax records
• Homes and other real estate
• Vehicles
• Personal property
• Business records

AccountingWeb wrote up a nice summary of the fact sheet, but for the details, see the original at the IRS website: Reconstructing Records After a Natural Disaster or Casualty Loss; IRS Provides Tips to Help Taxpayers | Internal Revenue Service.