Deductions & credits

Please see this from the IRS about reconstructing records after a natural disaster. There is helpful information that will answer your questions about determining what to use in Casualty and Loss section. The damage to your generator is also part of the casualty loss.

The Casualty and Theft section asks for information using terms that aren't commonly used.

• The Cost Basis is generally what was paid for the property
• Fair Market Value is generally the price for which the property could be sold to a willing buyer

The IRS  newsroom bulletin gives instructions to determine the Fair Market Value:

Determining the Decrease in Fair Market Value

Fair market value (FMV) is generally the price for which the property could be sold to a willing buyer. The decrease in FMV used to figure the amount of a casualty loss is the difference between the property's fair market value immediately before and after the casualty. FMV is generally determined through a competent appraisal. Without a competent appraisal, the cost of cleaning up or making certain repairs is acceptable under certain conditions as evidence of the decrease in fair market value.

Generally, the cost of cleaning up or making repairs if the repairs are:

• Actually made
• Not excessive
• Necessary to bring the property back to its condition before the casualty
• Only made to repair damage
• Not adding value to the property or making it worth more than before the disaster happened

The Cost Basis is what you paid for something, the Fair Market Value is what someone would pay for this after the casualty occurred. The Fair Market Value after the hurricane would be 0 if the items have no value after the event.