What happens if your business property — rather than your personal-use property — is stolen, vandalized or otherwise damaged by an event? The same basic casualty and theft loss rules generally apply, with a few notable exceptions.
Most important, the limits for individual casualty and theft loss deductions don’t apply. In other words, you don’t have to worry about the $100-per-event reduction or the 10%-of-AGI threshold. Business casualty and theft losses are fully deductible (subject to the other restrictions listed in the main article, such as those related to salvage value and insurance reimbursements).
As with income-producing property, if business property is destroyed, the amount of your loss is your adjusted basis in the property. Any decrease in fair market value doesn’t come into play.