Form 4684, Casualties and Theft.
If you use one of the safe harbor methods provided in Revenue Procedure 2018-08, you must attach a statement to Form 4684 stating that you used Revenue Procedure 2018-08 to determine the amount of your casualty loss. Include the specific safe harbor method used. When completing Form 4684, do not enter an amount on line 5 or line 6 for each property. Instead, enter the decrease in the FMV determined in the relevant safe harbor method on line 7.
I find it hard to believe that most filers would not use a safe harbor method. And with the number of FEMA disasters every year, this is a common form.
If TurboTax developers would not require lines 5&6 and have a field available for the Safe Harbor method, then at minimum, we could file a copy of the TurboTax worksheet.
