Summary
Form 4684 (Casualties and Thefts) is the IRS form taxpayers use to report gains or losses from casualty events (fires, floods, storms, vandalism, accidents, etc.) and thefts. Many personal casualty and theft losses are deductible only when they are attributable to a federally declared disaster. Business and income‑producing property follow different rules. This guide explains who can file, how losses are calculated, special disaster provisions, documentation to keep, and practical step‑by‑step filing instructions.
Key official sources
– IRS — Form 4684 and Instructions for Form 4684
– IRS — Publication 547, Casualties, Disasters, and Thefts
– Investopedia overview of Form 4684 (summary/background)
Who can file Form 4684
– Individuals, estates, and trusts reporting gains or deductible losses from casualties or thefts should complete Form 4684 and attach it to their Form 1040 (or an amended return).
– Business owners or owners of income‑producing property also use Form 4684 for casualty/theft events affecting that property; reported amounts may flow to business tax forms (Schedule C, Form 4797, etc.), depending on the type of property and business entity.
– Note: For personal‑use property, the Tax Cuts and Jobs Act (TCJA) suspended most personal casualty and theft loss deductions for tax years 2018–2025 unless the loss is attributable to a federally declared disaster. Casualty gains remain taxable and can be offset by casualty losses even if those losses are not from a declared disaster.
What qualifies as a casualty or theft loss
– Casualty: a sudden, unexpected, or unusual event (fire, flood, storm, hurricane, earthquake, vandalism, certain accidents). Damage from gradual deterioration or ongoing infestation (termites, mold) is generally not a casualty.
– Theft: larceny, embezzlement, and similar criminal acts (including some frauds) if the act is a crime under state law and involves criminal intent. Some financial losses (bank insolvency, Ponzi scheme losses) can qualify in special circumstances.
– Business and income‑producing property may have deductible casualty/theft losses even if not in a declared disaster—see Publication 547.
Basic calculation rules (personal‑use property)
1. Determine the amount of loss:
• Loss = lesser of (A) adjusted basis in the property, or (B) decrease in fair market value (FMV) as a result of the casualty.
2. Subtract any salvage value (amount you can recover by repairing or selling salvage).
3. Subtract any insurance or other reimbursements you actually receive or expect to receive.
4. For each separate casualty event, subtract $100 (the $100 rule).
5. Subtract 10% of your adjusted gross income (AGI) from the total of all casualty/theft losses for the year.
6. The remainder is the deductible casualty/theft loss (if any), generally reported on Schedule A (itemized deductions) unless special disaster rules apply.
Practical numeric example (personal property)
– Pre‑loss FMV of boat: $9,000; FMV after loss: $2,000 → decrease in FMV = $7,000
– Adjusted basis (what you paid minus depreciation, etc.): $8,500 → use lesser = $7,000
– Insurance reimbursement: $2,000 → net loss = $5,000
– Subtract $100 per casualty → 5,000 − 100 = 4,900
– AGI = $50,000 → 10% AGI = $5,000 → result after 10% AGI = 4,900 − 5,000 = 0 → no deductible loss this year
Important special rules and considerations
– Federally declared disasters (special rule): For qualified disaster losses, the rules permit additional relief:
• Personal casualty losses attributable to a federally declared disaster can be deducted even though other personal casualty losses are suspended under TCJA.
• Taxpayers may elect to claim a qualified disaster loss on the prior year’s tax return (which can accelerate a refund). Section D of Form 4684 and the Instructions explain how to report qualified disaster losses and make the election.
• Taxpayers living in a federally declared disaster area may be able to take disaster losses without itemizing in certain circumstances—follow the Form 4684 instructions and Publication 547 for details.
– Casualty gains: If the casualty produces a gain (for example, insurance proceeds exceed the adjusted basis), the gain is generally taxable and must be reported. Non‑disaster personal casualty losses can be used to offset casualty gains.
– Year to claim:
• Casualty: generally the year the casualty occurred.
• Theft: generally the year the theft is discovered.
– Business or income‑producing property: losses and gains are treated differently and generally are reported in different parts of Form 4684 and may pass through to business tax forms. Business casualty losses are often deductible regardless of whether the event was in a declared disaster.
– Certain unique cases: losses from bankrupt financial institutions, some Ponzi scheme losses, corrosive drywall, or specific concrete deterioration may have special guidance in Publication 547 and Form 4684 instructions.
Documentation checklist (what to keep)
– Photos or videos of damage before and after the event
– Insurance claims and settlement statements
– Police reports or other official theft reports
– Repair estimates or contractor invoices, itemized receipts
– Appraisals or valuations documenting FMV before and after (if available)
– Correspondence, demolition or building‑authority notices (for loss of structure or forced demolition after declared disaster)
– Records of any reimbursements received or expected
– Proof of discovery date for thefts (police report date, etc.)
Practical step‑by‑step: How to complete and file Form 4684
1. Confirm eligibility: determine whether the casualty/theft is deductible (personal vs. business, federal disaster rules, TCJA limits).
2. Gather documentation (see checklist above).
3. Determine the correct section of Form 4684:
• Use the section for personal property casualty/theft (and for casualty gains/losses from personal use property).
• Use the business/income‑producing property section if applicable.
• Use Section D for qualified federally declared disaster losses (and to elect prior‑year treatment when appropriate).
• (Refer to the current year Form 4684 and its Instructions for exact section labels and flow.)
4. Compute the loss using the calculation steps above (basis vs. FMV, subtract salvage/receipts, subtract $100 per event, subtract 10% of AGI).
5. Fill in Form 4684 completely and accurately; transfer the final deductible amount to Schedule A (for personal losses) or the appropriate business tax form.
6. If electing to claim a qualified disaster loss in the prior year, follow the Form 4684 instructions carefully for the election and file an amended prior year return if required (Form 1040‑X) or attach Form 4684 to the prior‑year return as instructed.
7. Keep copies of all documents and the completed form for at least three years (longer if the IRS advises or if fraud is involved).
Amending returns and timing
– If you discover a qualified disaster loss after you filed last year’s return and want to claim it on that prior year (permitted election), file the appropriate amended return or follow the Form 4684 instructions for making the election. The instructions provide the specific procedures and deadlines.
– For thefts discovered after the year of occurrence, report the loss in the year of discovery.
When you should consult a tax professional
– Complex situations: casualty gains, large losses, business vs. personal property questions, Ponzi scheme or financial institution failures, or when you want to elect prior‑year treatment for disaster losses.
– When your loss interacts with other tax issues (e.g., depreciation recapture, business casualty treatment, insurance settlements treated as income elsewhere).
– When multiple taxpayers, co-owners, or casualty allocations among owners are involved.
Where to get Form 4684 and help
– Form 4684 and its instructions: IRS.gov (search “Form 4684”)
– Publication 547, Casualties, Disasters, and Thefts: IRS.gov (search “Publication 547”)
– IRS disaster relief pages for current qualified disasters and special filing guidance
– Investopedia overview (for plain‑language summary and examples)
Selected official citations
– IRS, Form 4684 and Instructions for Form 4684 (available at IRS.gov)
– IRS, Publication 547, Casualties, Disasters, and Thefts
– Investopedia, “Form 4684: Casualties and Thefts” (background and examples)
Bottom line
Form 4684 is the form to report gains and losses from casualties and thefts. Calculate losses carefully (lesser of basis or FMV decline, minus salvage and reimbursements), apply the $100 per‑event and 10% of AGI limits for personal losses, and follow special rules for federally declared disasters. Keep thorough documentation and consult a tax professional when losses are large or the facts are complex.
– Walk through a specific example using your numbers (AGI, FMV before/after, basis, reimbursements).
– Point you to the exact lines on the current Form 4684 and Instructions for your tax year.
– Summarize step‑by‑step how to make the prior‑year disaster election for your situation.