Casualty Loss Deduction Calculator 2026
Measure a disaster loss from property basis and fair-market-value decline, remove insurance recovery, and apply the declaration gate, per-event reduction and AGI floor.
Document the casualty event
Cost plus capital improvements, reduced by prior depreciation and other basis adjustments.
The $100 reduction generally applies once per event, not once per damaged item.
Estimated personal casualty loss deduction
$0 approximate federal tax effect at the entered marginal rate
What changed for personal casualty losses in 2026
The federal limitation on personal-use casualty losses was made permanent and expanded beginning in 2026. A qualifying personal casualty loss is no longer restricted only to a federally declared disaster; a loss associated with a qualifying state-declared disaster may also enter the deduction calculation when the other requirements of Internal Revenue Code section 165 are met. The expansion does not make ordinary wear, gradual deterioration, misplaced property, or every uninsured accident deductible.
This calculator applies the general personal-use property method. It does not calculate business or income-producing property losses, theft losses from profit-seeking transactions, personal casualty gains, or special qualified-disaster relief enacted for a named event. Final 2026 Form 4684 instructions must define the state declaration and any required identifying number or attachment.
The starting loss is not the repair bill
Property loss before reimbursement: the smaller of adjusted basis or the decline in fair market value caused by the casualty.
Net casualty loss: starting property loss − insurance and other reimbursement received or reasonably expected.
General personal deduction: net loss − $100 per casualty event − 10% of AGI, never below zero.
A contractor’s repair estimate can help document damage, but it is not automatically the deductible loss. Fair market value is generally measured immediately before and after the event, often with a competent appraisal. Adjusted basis is usually cost plus capital improvements, reduced by depreciation, prior casualty deductions, insurance reimbursements that reduced basis, and other required adjustments. A home worth $500,000 can have a much lower tax basis, so the basis ceiling can control even when economic damage is severe.
The cost of repairs may support a decrease-in-value estimate under permitted conditions when repairs are necessary to restore the property, are not excessive, address only the damage, and do not increase value above the pre-casualty condition. IRS safe-harbor methods can apply to certain personal residences and belongings. Choose one defensible method and retain its documentation; do not add repair cost to an appraisal decline for the same damage.
Insurance and reimbursement come before tax floors
Subtract insurance proceeds, grants, employer assistance, or other reimbursement that compensates the same loss. If a claim remains unresolved and reimbursement is reasonably expected, the loss may not be sustained until the expectation is resolved. Later reimbursement greater or smaller than expected can require an amended computation or income under the tax-benefit rule.
A taxpayer generally must file a timely insurance claim for covered property to deduct the portion that insurance could have reimbursed. Choosing not to claim in order to create a tax deduction is not a substitute for the claims process. The calculator therefore sets the deduction to zero when the user says coverage existed but no timely claim was filed. It cannot decide whether an exclusion, deductible, policy limit, or denied claim was reasonable.
How the $100 event rule and AGI floor work
The $100 reduction applies to each casualty event after reimbursement, not to every damaged asset. If one wildfire damages a home, a detached garage, and personal belongings, the losses are generally combined for the single-event reduction. Two unrelated storms can produce two reductions. Married taxpayers filing jointly apply one reduction per event; separate owners and separate returns can require individual treatment.
After the event reduction and coordination with any personal casualty gains, the general loss is reduced by 10% of adjusted gross income. With $120,000 of AGI, the floor is $12,000. The floor does not mean the first 10% of repair spending is a medical-style threshold; it is applied to the calculated net casualty loss at the specified stage of Form 4684. A high AGI can eliminate a moderate uninsured loss.
| Input | Example amount | Form 4684 role |
|---|---|---|
| Adjusted basis | $240,000 | Maximum property loss before reimbursement |
| FMV decline | $125,000 | Compared with basis; smaller amount wins |
| Insurance | $70,000 | Leaves $55,000 before personal-use reductions |
| One-event reduction | $100 | Leaves $54,900 |
| 10% of $120,000 AGI | $12,000 | Leaves a $42,900 estimated deduction |
Federal versus state declaration checkpoint
For a federal disaster, retain the FEMA disaster declaration number and confirm that the property is in the covered state or eligible area for the type of claim. The term “disaster loss” can be narrower than a general federal casualty loss when preceding-year elections or public/individual assistance areas are involved. The year in which the loss is sustained also can depend on reimbursement prospects.
For a 2026 state-declared event, keep the governor or authorized state declaration, covered dates, geographic area, and evidence connecting the property damage to that event. Because this category begins in 2026, the final Form 4684 and Publication 547 revision should control terminology. A city emergency announcement, insurer catastrophe code, or news description may not by itself meet the federal definition.
Without a qualifying declaration, this calculator returns zero for the ordinary personal-use deduction. A separate exception can allow non-disaster personal casualty losses to offset personal casualty gains, and business or profit-seeking property follows different rules. Those paths require a broader Form 4684 computation and are intentionally not disguised inside this personal disaster estimator.
Timing and basis after the loss
A casualty loss is generally deducted in the year it is sustained, which can be later than the physical event when a reasonable prospect of reimbursement exists. Eligible federally declared disaster losses may permit an election to deduct in the preceding year, subject to deadlines and area requirements. The 2026 state-declaration expansion should not be assumed to carry every federal-disaster election without checking final guidance.
Insurance proceeds and an allowed casualty deduction can reduce the property’s adjusted basis. Restoration spending may then increase basis when it is a capital improvement rather than a currently deductible repair. If reimbursement exceeds adjusted basis, a casualty gain can arise and replacement-property deferral rules may be relevant. This calculator estimates the loss deduction only; it does not update the property’s post-casualty basis or compute gain deferral.
Records that make the estimate defensible
Keep proof of ownership, original purchase records, improvement invoices, prior depreciation schedules, photographs before and after the event, appraisals, repair contracts, insurance policies, claims correspondence, settlement statements, government grants, declaration notices, maps of the covered area, and a timeline of reimbursement expectations. Separate temporary living costs from property loss because they follow different tax and insurance rules.
Entering this deduction there still requires checking whether Schedule A, special disaster rules, or another return line applies. This calculator supplies the casualty waterfall, not a completed federal return.
Frequently asked questions
Can I use the amount of my insurance deductible as the casualty loss?
Not automatically. The tax loss begins with the smaller of adjusted basis or FMV decline, then subtracts reimbursement and applies the personal-use reductions. An insurance deductible is only one policy feature.
Does every damaged item receive a separate $100 reduction?
No. The reduction generally applies once to each casualty event. Multiple items damaged by the same identifiable event are combined before applying that event’s reduction.
Does a state disaster qualify before 2026?
The expansion described by the IRS begins in 2026. Earlier personal-use losses generally relied on federally declared disaster status under the applicable law, subject to other exceptions and special legislation.
What if insurance pays me next year?
The loss may remain unresolved while reimbursement is reasonably expected. A later payment can change the year or amount of the deduction and may trigger the tax-benefit rule. Use the claims timeline and final instructions.
Can business property use this calculator?
No. Business and income-producing property can use different measurement, reimbursement, depreciation, gain, and Form 4684 sections. This module is explicitly limited to personal-use property under the general disaster-loss floors.
References
- IRS casualty loss deduction expansion — official notice that qualifying state-declared disasters enter scope beginning in 2026.
- IRS Publication 547, Casualties, Disasters, and Thefts — loss measurement, reimbursement, declaration and deduction-limit mechanics.
- IRS Topic No. 107, Tax Relief in Disaster Situations — federal declaration numbers, Form 4684 and disaster records.
- IRS Form 4684 information — casualty and theft gain/loss reporting.