What this line means
Your deductible personal casualty loss after all reductions: the $100 per-event floor, netting against casualty gains, and subtracting 10% of your adjusted gross income. This final amount transfers to Schedule A as an itemized deduction. For most moderate-income filers, the 10% AGI threshold eliminates most or all of the deduction, making significant losses deductible only for large disasters or low-income filers.
Does this apply to you?
- You have net casualty losses from federally declared disasters that exceed 10% of your AGI
- You itemize deductions on Schedule A and need to include your casualty loss
- You experienced a major property loss and want to know the actual tax benefit
Easy to overlook
The 10% AGI threshold is substantial If your AGI is $80,000, you subtract $8,000 from your total losses (after the $100 per-event reduction and netting against gains). A $10,000 loss yields only a $2,000 deduction. A $5,000 loss yields zero. This threshold eliminates casualty deductions for most filers unless the loss is very large relative to income. 1 IRS Publication 547 — Casualties, Disasters, and Thefts
You must itemize to claim the deduction The casualty loss deduction appears on Schedule A. If your total itemized deductions (including the casualty loss) do not exceed the standard deduction, you are better off taking the standard deduction and the casualty loss provides no tax benefit. For 2025, the standard deduction is $15,750 (single) or $31,500 (married filing jointly). 2 IRS Form 4684 instructions — Line 18
Watch out for this
Claiming the casualty loss deduction without itemizing. Line 18 flows to Schedule A, line 15. If you take the standard deduction, the casualty loss produces no tax benefit. Run the numbers both ways — total itemized deductions with the casualty loss versus the standard deduction — and use whichever is larger.
Footnotes
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IRS Publication 547, Casualties, Disasters, and Thefts, 10% Rule. https://www.irs.gov/pub/irs-pdf/p547.pdf ↩
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IRS Form 4684 Instructions, Line 18. https://www.irs.gov/instructions/i4684 ↩