Report casualty and theft losses on IRS Form 4684 Casualties and Thefts PDF. ("Business" - Business Income" - "Business Assets" "Tell us more about this asset" - and select "This item was sold, retired, stolen, destroyed...." Enter the date, then "Continue" and select "Yes" at the next screen as it was destroyed due to casualty (one of the stipulations of selecting "Yes").
Use Section A for personal-use property and Section B for business or income-producing property. For losses involving business-use property, refer to IRS Publication 584 - Business Casualty Losses
