To show a loss on your taxes, you report it on the form that matches the type of loss: Schedule C for a sole proprietor business, Form 8949 with Schedule D for investment losses, Schedule E for rental real estate, and Form 4684 for casualty and theft losses. Each form carries its own documentation demands and deduction limits, and the IRS can throw out any loss you can’t back up with records.1eCFR. 26 CFR 1.165-1 – Losses
Documentation the IRS Expects for Any Loss
A deduction is available only for losses not reimbursed by insurance or other compensation, and only when you can prove the loss happened and how much it cost you.1eCFR. 26 CFR 1.165-1 – Losses That means receipts, canceled checks, invoices, and bank statements for every expense or transaction feeding into the number on your return.
If the loss comes from selling property or an asset, you need records that establish your cost basis: what you paid, plus improvements and transaction costs like legal fees or closing costs.2Internal Revenue Service. Publication 551 (12/2025), Basis of Assets Without basis documentation, the IRS can treat your basis as zero, which erases the loss or turns it into a gain. Purchase contracts, closing statements, and brokerage confirmations do this work.
Casualty and theft claims add another layer. For a casualty, you have to show you owned the property, what happened, when it happened, and whether you filed an insurance claim. For theft, you need evidence the property was stolen and when you discovered it gone.3Internal Revenue Service. Publication 547 (2025), Casualties, Disasters, and Thefts A competent appraisal showing value before and after the event is the standard way to quantify the drop.
Keep loss records at least three years after filing. For worthless securities or bad debts, the retention window stretches to seven.4Internal Revenue Service. How Long Should I Keep Records? For property generating depreciation or a carryforward, hold the records until the limitations period runs on the year you dispose of it.
Business Losses on Schedule C
Sole proprietors and single-member LLCs report income and expenses on Schedule C. When total expenses exceed gross receipts, the result is a net loss, but you can’t drop that figure onto line 31 without first running it through the at-risk rules and the passive activity rules.5Internal Revenue Service. Instructions for Schedule C (Form 1040) (2025) The Schedule C instructions are explicit about applying both filters before you enter a loss.
Once cleared, the loss flows to Schedule 1 of Form 1040 and offsets other income like wages or interest. Every expense line has to tie back to your documentation. Inaccurate figures can trigger a 20% accuracy-related penalty on the underpayment.6Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments
At-Risk and Passive Activity Filters
The at-risk rules cap your deductible loss at what you actually have on the line: cash you invested, property you contributed, and amounts you borrowed for which you’re personally liable. Nonrecourse debt and amounts protected by guarantees don’t count.7Office of the Law Revision Counsel. 26 U.S. Code 465 – Deductions Limited to Amount at Risk Losses blocked here carry forward until you have enough at-risk basis to absorb them.
Whatever survives that filter runs into the passive activity rules. If you don’t materially participate in a business activity, any loss is passive and can only offset other passive income, not wages, interest, or portfolio gains.8Office of the Law Revision Counsel. 26 U.S. Code 469 – Passive Activity Losses and Credits Limited The IRS uses seven tests to determine material participation; the most straightforward is more than 500 hours in the activity during the year.9Internal Revenue Service. Publication 925 (2025), Passive Activity and At-Risk Rules Limited partners are generally treated as not materially participating regardless of hours worked. Disallowed passive losses carry forward and are fully released when you sell your entire interest in a taxable transaction.
Excess Business Loss Cap
Before a loss can even become a net operating loss, another ceiling applies. For 2026, noncorporate taxpayers cannot deduct business losses exceeding $256,000 ($512,000 on a joint return) beyond their total business income for the year. Anything above that is disallowed for the current year and treated as an NOL carryforward.10Internal Revenue Service. Excess Business Losses The calculation happens on Form 461, after the passive activity and at-risk rules have already taken their cut.
Net Operating Loss Carryforwards
When a business loss wipes out all your other income for the year, the leftover becomes a net operating loss. You carry an NOL forward to future years, where it can offset up to 80% of that year’s taxable income.11Internal Revenue Service. Tax Cuts and Jobs Act – A Comparison for Businesses The 80% ceiling means at least 20% of income remains taxable in any year you use an NOL carryforward.
Rental Real Estate Losses on Schedule E
Rental real estate goes on Schedule E, and all rental activity is automatically classified as passive. Losses normally can’t offset your wages or business income.12Internal Revenue Service. 2025 Instructions for Schedule E (Form 1040)
There is one escape hatch. If you actively participate in managing the property (approving tenants, setting rents, authorizing repairs), you can deduct up to $25,000 in rental losses against nonpassive income each year. The $25,000 allowance phases out once modified adjusted gross income exceeds $100,000 and disappears entirely at $150,000.9Internal Revenue Service. Publication 925 (2025), Passive Activity and At-Risk Rules If you’re married filing separately and lived with your spouse at any point during the year, the allowance drops to zero. Losses that exceed the allowance or fall out through the phase-out carry forward under the passive activity rules until you have passive income to absorb them or you sell the property.
Capital and Investment Losses on Form 8949
Losses from selling stocks, bonds, mutual funds, or other capital assets go on Form 8949, with totals rolling to Schedule D. For each transaction you list the asset, acquisition and sale dates, the proceeds, and your cost basis.13Internal Revenue Service. About Form 8949, Sales and Other Dispositions of Capital Assets Holding period determines whether the loss is short-term (one year or less) or long-term (more than one year).
Capital losses first offset capital gains of the same type. After netting, up to $3,000 of remaining loss deducts against ordinary income like wages each year ($1,500 if married filing separately).14Internal Revenue Service. Topic No. 409, Capital Gains and Losses Anything above that carries forward with no expiration. Losses from selling personal-use property such as a car or furniture are never deductible.
Wash Sales
Sell a stock at a loss and buy the same or a substantially identical security within 30 days before or after the sale, and the loss is disallowed under the wash sale rule.15Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss From Wash Sales of Stock or Securities The disallowed loss isn’t gone; it gets added to the basis of the replacement shares, deferring the tax benefit until you sell those shares without triggering another wash sale. This catches investors who sell a losing position in December and buy it back in January.
Worthless Securities and Section 1244 Stock
When a security becomes completely worthless, the IRS treats it as though you sold it for zero on the last day of the tax year. That deemed sale date sets short-term or long-term treatment. Report it on Form 8949 like any other capital loss, and hold the records for seven years instead of three.16Internal Revenue Service. Losses (Homes, Stocks, Other Property) 1
If you held qualifying Section 1244 small business stock, losses on that stock are treated as ordinary rather than capital, up to $50,000 per year ($100,000 on a joint return).17Office of the Law Revision Counsel. 26 USC 1244 – Losses on Small Business Stock They bypass the $3,000 capital loss cap and offset income dollar for dollar up to those limits. The stock must have been issued directly to you by a domestic small business corporation; secondary-market purchases don’t qualify.
Casualty and Theft Losses on Form 4684
Casualty and theft losses on personal-use property go on Form 4684. Since 2018, these are deductible only if the damage resulted from a federally declared disaster.18Internal Revenue Service. Instructions for Form 4684 (2025) A tree falling on your house during a hurricane with a FEMA declaration qualifies; a tree falling in an ordinary storm does not. You’ll need the FEMA disaster declaration number on the form.
For qualifying disaster losses, each event is reduced by $500. Then you subtract insurance reimbursements. The IRS requires you to file a timely insurance claim if coverage exists, or you lose the portion that would have been covered.19Internal Revenue Service. 2025 Instructions for Form 4684 – Casualties and Thefts The 10% of AGI threshold that historically applied to personal casualty losses does not apply to qualified disaster losses.3Internal Revenue Service. Publication 547 (2025), Casualties, Disasters, and Thefts
Business-use property follows different rules. Casualty losses on property used in a trade or business don’t require a federal disaster declaration and are reported in Section B of Form 4684.20Internal Revenue Service. Form 4684, Casualties and Thefts (2025) You can also elect under Section 165(i) to deduct a federally declared disaster loss on the prior year’s return rather than waiting, which can generate an immediate refund.
When the IRS Calls It a Hobby
Many Schedule C losses fall apart here. If the IRS determines your activity isn’t a genuine business, it reclassifies as a hobby, and hobby losses aren’t deductible. You still owe tax on any hobby income, but you can’t use expenses to offset it.
There is a safe harbor. If the activity turned a profit in at least three of the last five tax years (two of seven for horse breeding, training, showing, or racing), the IRS presumes you’re in it for profit.21Office of the Law Revision Counsel. 26 U.S. Code 183 – Activities Not Engaged in for Profit Falling outside the safe harbor doesn’t automatically make the activity a hobby; it means the IRS can challenge your profit motive.
Without the presumption, the IRS weighs whether you run the activity in a businesslike manner, your expertise, the time and effort you invest, whether losses come from startup costs or circumstances beyond your control, and whether you depend on the income.22Internal Revenue Service. Is Your Hobby a For-Profit Endeavor? No single factor decides it. Years of losses from an activity that looks recreational will draw scrutiny.
Claiming a Missed Loss on a Prior Return
If you discover a deductible loss you didn’t claim, file Form 1040-X to amend the return. The general deadline is three years from the date you filed the original return, or two years from the date you paid the tax, whichever is later.23Internal Revenue Service. Time You Can Claim a Credit or Refund Miss that window and the loss is gone.
A longer window applies to worthless securities and bad debts: seven years from the due date of the return for the year the security became worthless or the debt went bad.24Internal Revenue Service. Topic No. 305, Recordkeeping The extended period exists because pinpointing the exact year of worthlessness is often difficult. When the year is unclear, filing protective claims for multiple years is common practice.