Casualty and Disaster Losses
After a fire, a flood or a storm, the tax treatment is rarely the first concern and it is worth understanding once things settle. For most taxpayers a personal casualty loss is deductible only where it arose in a federally declared disaster, and even then three reductions apply before anything reaches the return. One provision is genuinely valuable: the loss can be claimed a year early.
- Federal declaration required:: For most taxpayers, losses outside a declared disaster area are not deductible.
- Measured at the lower figure:: The lesser of the decrease in fair market value or your adjusted basis in the property.
- Three reductions:: Insurance reimbursement first, then a per-event floor, then ten percent of adjusted gross income.
- The prior-year election:: A disaster loss can be claimed on the previous year's return, producing a refund sooner.
Where the AI summary above gets this wrong
"You can deduct losses from a fire or flood on your taxes."
That's surface-true. Here's what it misses:
- Personal casualty losses are mostly not deductible any more — For most taxpayers the deduction now applies only to losses attributable to a federally declared disaster. A house fire, a burst pipe or a theft outside such a declaration produces no deduction at all, which reverses what many people remember from earlier rules.
- The ten percent reduction removes most of what is left — After insurance and the per-event floor, ten percent of adjusted gross income is subtracted. For a household with moderate income, that alone eliminates all but a substantial loss — and the remainder only helps if the household itemises, which after the higher standard deduction most retirees do not.
- Claiming it a year early is the provision that matters — A loss in a federally declared disaster can be claimed on the return for the previous year, either by amending it or on a return not yet filed. That produces a refund months sooner, which is worth far more to a household rebuilding than the same amount arriving a year later.
01 What qualifies
A casualty is damage or loss from an event that is sudden, unexpected or unusual — a storm, a fire, a flood, a vehicle accident. Gradual deterioration, poor maintenance and most pest damage do not qualify, because they are not sudden.
For most individual taxpayers the deduction is now limited to losses attributable to a federally declared disaster. Whether an event carries that declaration is a matter of public record and determines everything that follows.
Theft losses follow related rules and are subject to the same limitation for personal property. Losses on property used in a business or held for investment are treated differently and are not subject to the disaster requirement.
02 How the amount is computed
Start with the smaller of two figures: the decrease in the property's fair market value caused by the event, or your adjusted basis in it. For a long-held house that basis is frequently far below current value, which caps the loss well below what replacement would cost.
Subtract any insurance or other reimbursement, including amounts you could have claimed and did not — declining to file a claim does not increase the deduction. Then subtract a fixed amount per event, and then ten percent of adjusted gross income.
Establishing basis matters here more than usual. Purchase records and the cost of improvements over the years are what support the figure, and they are the documents most likely to have been destroyed by the event itself — which is an argument for keeping them somewhere other than the house.
Shows: a personal casualty loss after subtracting insurance reimbursement, the per-event floor, and ten percent of adjusted gross income. Ignores: that the loss must arise in a federally declared disaster to be deductible at all for most taxpayers, the separate rules for qualified disaster losses, and whether itemising is worthwhile once it is computed.
Source: Publication 551
03 The prior-year election
A loss in a federally declared disaster can be claimed on the return for the year before the disaster, rather than the year it occurred. Where the earlier return has been filed, it is amended; where it has not, the loss simply goes on it.
The advantage is timing. A refund arrives months earlier than it otherwise would, at exactly the point a household is paying for temporary accommodation and repairs.
The choice is also worth making on the arithmetic. The ten percent reduction is a percentage of that year's adjusted gross income, so the year with lower income produces the larger deduction — and for someone whose income fell after retiring, the two years can differ enough to matter alongside the wider income planning.
Source: Publication 547
The tax question is not the important one in the weeks after a disaster, and there is one thing worth doing early: find out whether the event carried a federal declaration, because everything else follows from that. If it did, ask whoever prepares your return to compare claiming the loss this year against last. The refund arriving six months sooner is worth more than the difference in the deduction, and both point the same way for most households.
FAQ
Can I deduct a loss from a house fire?
For most taxpayers, only if it was attributable to a federally declared disaster. Outside such a declaration, personal casualty losses are generally not deductible.
How is the deductible loss calculated?
The lesser of the decrease in fair market value or your adjusted basis, minus insurance reimbursement, minus a per-event floor, minus ten percent of adjusted gross income.
Can I claim a disaster loss on last year's return?
Yes, for a federally declared disaster. Claiming it on the prior year's return produces a refund sooner, and the year with lower income yields the larger deduction.
Sources
Regulator references
- Topic 515: casualty, disaster and theft losses · Internal Revenue Service · 2026When a loss is deductible and the federally declared disaster requirement.Last verified: 2026-09-07
- Publication 547 · Internal Revenue Service · 2026How the loss is computed and the election to claim it in the prior year.Last verified: 2026-09-07
- Publication 551 · Internal Revenue Service · 2026The adjusted basis a casualty loss is measured against.Last verified: 2026-09-07
Calculator unit tests · the assertions this page's worked example is checked against, and their last result
Changelog
- 2026-09-07 — initial publish (new format)
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Jordan Reeves
Founder of Talk Through Wealth. A software engineer for over a decade before turning to retirement planning, Jordan built the projection engine after watching family members get fragmented, country-by-country advice that never reconciled. He writes about retirement the way the engine computes it: month-by-month, lifetime-long, and skeptical of any rule of thumb that hasn't been run through the math.