IRS Publication 547: Casualties, Disasters & Thefts
When disaster strikes — a hurricane, wildfire, flood, or theft — the tax code offers relief, but only under strict conditions. Publication 547 defines what counts as a casualty, how to calculate your loss, the federal disaster declaration requirement for personal losses, and the documentation the IRS demands. Getting it wrong can mean losing thousands in legitimate deductions — or worse, triggering an audit.
How to Calculate Your Casualty or Theft Loss
Step 1: Determine Adjusted Basis
Your adjusted basis is generally what you paid for the property plus the cost of any permanent improvements, minus any depreciation claimed. For inherited property, basis is typically the fair market value at the date of death. For personal-use property like your home or car, basis is your purchase price plus major improvements (a new roof, an addition) — not routine maintenance.
Step 2: Calculate Decline in Fair Market Value
Determine the FMV immediately before and immediately after the casualty. The difference is the decline in value. An appraisal is the gold standard. Repair costs can substitute if they are reasonable, necessary, and actually completed — but they cannot exceed the pre-casualty FMV. Photographs, insurance adjuster reports, and comparable sales data all help substantiate the decline.
Step 3: Take the Lesser of Basis or FMV Decline
Your loss before reimbursements is the SMALLER of: (a) your adjusted basis, or (b) the decline in FMV. If your basis is $200,000 and the FMV dropped by $50,000, your pre-insurance loss is $50,000. If the property is completely destroyed, the loss is your adjusted basis minus any salvage value.
Step 4: Subtract Insurance & Other Reimbursements
Subtract any insurance proceeds, FEMA grants, disaster relief payments, or other reimbursements you received or expect to receive. You MUST file a timely insurance claim if the property is insured — you cannot skip filing to claim a larger deduction. If you receive more in insurance than your adjusted basis, you may have a taxable gain.
Step 5: Apply the $100 & 10% AGI Limits (Personal Losses Only)
For personal-use property: subtract $100 per casualty event from each loss, then combine all losses for the year. From that total, subtract 10% of your adjusted gross income. Only the excess is deductible. Example: AGI of $80,000, two disaster losses of $7,000 and $3,000. Subtract $100 from each ($6,900 + $2,900 = $9,800 total). Subtract $8,000 (10% of $80,000 AGI). Deductible amount: $1,800.
The "Sudden, Unexpected, or Unusual" Test
Qualifies as a Casualty
Hurricanes, tornadoes, earthquakes, floods, wildfires, lightning strikes, volcanic eruptions, and severe storms. Vandalism and theft also qualify. A car accident not caused by your willful negligence counts. A mine cave-in or shipwreck is a casualty. The key: the event must be identifiable, discrete, and destructive in a sudden way.
Does NOT Qualify
Termite or moth damage over multiple years, progressive foundation settling, gradual water seepage causing mold or rot, damage from drought or disease that kills plants slowly, and normal wear and tear. Breaking an item out of anger or carelessness does not count as a casualty. Loss of property value due to a nearby landfill or noisy airport is NOT a casualty — no physical damage occurred.
Special Rule: Corrosive Drywall
The IRS issued special guidance for homeowners with corrosive drywall (imported drywall that emits sulfur compounds). Damage from corrosive drywall may qualify as a casualty loss if the damage is sudden — meaning the drywall was installed, then over time corroded wiring and pipes until they failed. The loss is treated as occurring when the homeowner first discovers the damage.
Special Rule: Ponzi Scheme Losses
Losses from Ponzi-type investment schemes are treated as theft losses rather than capital losses. This is significant because it allows the loss to be deducted as an itemized deduction rather than being subject to the $3,000 annual capital loss limit. IRS Revenue Procedure 2009-20 provides a safe harbor for calculating the deductible amount. The theft loss is treated as occurring in the year the fraud is discovered.
Business Casualty Losses — Fully Deductible
No Federal Disaster Requirement
Business property and income-producing property (rental real estate, equipment, inventory) are NOT subject to the TCJA federal disaster declaration requirement. A business casualty loss is fully deductible in the year it occurs, regardless of FEMA involvement. This is a critical distinction from personal losses.
No $100 or 10% AGI Limits
The $100 per event reduction and the 10% of AGI floor apply ONLY to personal-use property. Business casualty losses have neither limitation. If your rental property suffers $30,000 in uninsured flood damage and the event is not federally declared, the entire $30,000 is deductible against your rental income.
Complete Destruction of Business Property
If business property is completely destroyed, the loss equals your adjusted basis minus any salvage value and insurance. If the property is partially destroyed, use the same lesser-of-basis-or-FMV-decline test. Repairs that restore the property to pre-casualty condition are generally deductible as a business expense rather than a casualty loss — but you cannot claim both for the same damage.
Reporting on Form 4684
Business casualty losses are reported on Form 4684, Section B (Business and Income-Producing Property). The loss then flows to your business return: Schedule C for sole proprietorships, Schedule E for rental properties, Schedule F for farms, or Form 1120/1065 for corporations and partnerships. You must reduce the property's basis by the amount of the loss claimed and any insurance received.
Filing & Documentation Requirements
Form 4684 — Casualties and Thefts
All casualty and theft losses are reported on Form 4684. Section A covers personal-use property (with the federal disaster test). Section B covers business and income-producing property. The form walks through the loss calculation step by step, including the $100 and 10% AGI reductions for personal losses. The resulting deduction flows to Schedule A (itemized deductions) for personal losses.
Disaster-Year Election
For losses in federally declared disaster areas, you can elect to deduct the loss on your PRIOR year's tax return. This gets you a refund faster — you file an amended return (Form 1040-X) for the prior year, attaching Form 4684. The election must be made by the due date (with extensions) of the return for the disaster year. Once made, the election is irrevocable.
Proof of Loss Documentation
Keep: insurance claims and settlement statements, FEMA determination letters, appraisals (before and after), repair receipts, photographs or video of the damage, police reports for theft and vandalism, newspaper clippings about the disaster, and proof of your basis (purchase records, closing statements, improvement receipts). The IRS will disallow a loss without adequate substantiation.
When Insurance Exceeds Basis
If your insurance reimbursement exceeds your adjusted basis in the property, you have a taxable gain. However, for personal-use property damaged in a federally declared disaster, you may defer the gain if you purchase replacement property within the replacement period (generally 2 years for personal property, 4 years for your main home in a disaster area). Report on Form 4684 and Form 8824 (like-kind exchanges) if applicable.