Compute casualty or disaster gain or loss on IRS Form 4684.  Carry the result to Form 4797 if a business or investment property casualty and/or Schedule A for other allowed casualties. (If Form 4797 isn’t otherwise required, the net casualty gain or loss can be entered on Form 1040, Schedule 1, line 4 with “Form 4684” entered next to the line 4 amount (2023 Form 4684 instructions, page 8)).  Appraisal fees related to establishing the value of property lost in a casualty are deductible as Tier 2 expenses on Schedule A, but for years 2018-2025 when the TCJA suspends the deduction of Tier 2 expenses, none of the appraisal fees will be deductible.