A deferred loss is an economic loss you have actually incurred but that the tax code won’t let you deduct in the year it happened. The sale is real, the money is gone, and the loss is calculated — but a specific rule postpones the deduction until a later triggering event occurs. Several different rules can cause this delay, and each has its own conditions for when the loss finally becomes usable. Knowing which rule suspended your loss is the key to knowing when, or whether, you’ll get to claim it.
Why Losses Get Deferred
The tax code contains several separate mechanisms that push a loss into a future year rather than allowing it in the year of the sale. The most common are:
- The wash sale rule, which blocks losses on stock or securities when you buy the same thing back too quickly.
- The related party rules under Section 267, which disallow losses on sales between family members and certain controlled entities.
- The passive activity loss rules under Section 469, which limit losses from activities you don’t materially participate in.
- Basis and at-risk limitations, which cap losses passed through from partnerships and S corporations.
For partners and S corporation shareholders, these filters apply in a required order: basis first, then at-risk, then passive activity, then the excess business loss cap under Section 461(l).1Internal Revenue Service. Publication 925, Passive Activity and At-Risk Rules A loss stopped at the first step never reaches the later ones, and each layer has its own carryforward rules. Misidentifying which rule caught your loss leads directly to misidentifying when you can claim it.
Wash Sale Losses
If you sell a stock or security at a loss and buy substantially identical shares within a 61-day window — the 30 days before the sale, the sale date itself, and the 30 days after — the loss is disallowed for that year.2Office of the Law Revision Counsel. 26 USC 1091 – Loss From Wash Sales of Stock or Securities
The good news with a wash sale is that the loss isn’t destroyed. It is added to the cost basis of the replacement shares. When you eventually sell those replacement shares in a transaction that doesn’t itself trigger another wash sale, the deferred amount comes back to you as either a larger loss or a smaller gain.
Say you sell 100 shares for $9,000 that you had bought for $10,000. Two weeks later you repurchase 100 shares of the same company for $9,200. The $1,000 loss is disallowed. Instead of a $9,200 basis, your replacement shares carry a $10,200 basis, and that extra $1,000 shows up whenever you close out the new position.
What Counts as Substantially Identical
Common stock of the same corporation is the clearest case. Contracts and options to acquire the same security count too, so buying a call option on the same stock within the window triggers the rule.3Investor.gov. Wash Sales Selling one company and buying a competitor in the same industry is generally fine. Two ETFs tracking the same index with nearly identical holdings are risky ground, and the IRS has not issued a bright-line test.
The IRA Trap
The wash sale rule applies across all your accounts, including your IRA. If you sell shares at a loss in a taxable account and buy substantially identical shares in your IRA within the 61 days, the loss is disallowed. Because IRA holdings aren’t tracked with individual cost basis in the ordinary way, Revenue Ruling 2008-5 effectively treats the disallowed loss as permanently lost rather than deferred. This is one of the most expensive wash sale mistakes, since the basis adjustment that normally preserves the loss can’t function inside a tax-sheltered account.
Cryptocurrency
The wash sale rule applies only to stock or securities. Cryptocurrency is currently classified as property, not a security, so selling Bitcoin at a loss and immediately repurchasing does not trigger a wash sale. Proposals to extend the rule to digital assets have been floated but not enacted as of 2026.
Related Party Losses
When you sell property at a loss to a related party, your loss is disallowed entirely.4Office of the Law Revision Counsel. 26 USC 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers The sale is valid; you simply can’t deduct the loss. The logic is that a sale to your sibling doesn’t change the family’s overall economic position.
The definition of related party is broader than most people expect. It covers siblings (whole or half blood), spouses, ancestors, and lineal descendants. In-laws and step-relatives are not included in the statutory family definition. It also covers an individual and a corporation in which that individual owns more than 50 percent of the stock, along with various trust, estate, and controlled-entity combinations. Constructive ownership rules treat you as owning stock held by family members and by entities you own, which can pull transactions into the rule even when your direct ownership looks small.
How the Loss Comes Back — Sometimes
The seller’s disallowed loss shifts to the buyer, but only in a limited way. When the buyer later sells the property to an unrelated third party at a gain, the buyer’s gain is reduced by the seller’s previously disallowed loss. The disallowed loss can offset a gain, but it cannot create or increase a loss for the buyer.4Office of the Law Revision Counsel. 26 USC 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers
Suppose you sell stock to your sister for $80,000 that cost you $100,000. Your $20,000 loss is disallowed. If she later sells to a stranger for $95,000, her $15,000 gain is offset by $15,000 of your disallowed loss, and the remaining $5,000 of your loss simply disappears. If she instead sells for $75,000, she has her own $5,000 loss and your $20,000 provides no benefit to anyone. This makes related-party deferral the riskiest kind: the loss may never be deductible at all.
Passive Activity Losses
The passive activity rules are the deferral most taxpayers run into. They prevent losses from activities you don’t actively run from offsetting your wages, business income, or portfolio income.5Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited An activity is passive if it’s a trade or business you don’t materially participate in, or any rental activity regardless of your involvement. If your total passive losses exceed your total passive income for the year, the excess is suspended and carried forward on Form 8582. The suspended amount stays attached to the specific activity that generated it.
Material participation is measured through seven tests in the regulations, and satisfying any one of them makes an activity non-passive. The most common are participating more than 500 hours during the year, doing substantially all the work in the activity, or participating more than 100 hours with no one else participating more. Keep contemporaneous time logs; courts have been unsympathetic to taxpayers who reconstruct hours after the fact.1Internal Revenue Service. Publication 925, Passive Activity and At-Risk Rules
The $25,000 Rental Allowance
Rental activities are automatically passive, but there is a partial exception. If you actively participate in a rental real estate activity — a lower bar than material participation, essentially making management decisions like approving tenants or repairs — you can deduct up to $25,000 of rental losses against non-passive income.5Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited The allowance phases out by 50 cents for every dollar of modified adjusted gross income above $100,000 and disappears at $150,000. These thresholds are set by statute and are not indexed for inflation. A separate exemption exists for qualifying real estate professionals who spend more than 750 hours annually in real estate trades or businesses and more than half their working time in those activities.
When Suspended Passive Losses Are Released
Suspended passive losses become fully deductible when you dispose of your entire interest in the activity in a fully taxable transaction to an unrelated party. Both “entire interest” and “fully taxable” matter. Selling 80 percent of a rental property is not enough. Neither is a tax-free exchange.
When the trigger is met, the released losses first offset any gain on the disposition, and whatever remains can offset non-passive income like wages or portfolio income. This is one of the few moments where passive losses cross the barrier into reducing ordinary income tax.
A smaller release happens when a formerly passive activity becomes active because you start materially participating. Prior suspended losses can then offset current-year net income from that same activity, but any excess remains treated as a passive loss.1Internal Revenue Service. Publication 925, Passive Activity and At-Risk Rules
Basis and At-Risk Suspensions
If you’re a partner or S corporation shareholder, losses passed through to you have to clear two hurdles before they can even reach the passive activity screen.
First, your deductible share can’t exceed your adjusted basis. For partners, that’s your basis in the partnership interest at year-end.6Office of the Law Revision Counsel. 26 USC 704 – Partners Distributive Share For S corporation shareholders, it’s your stock basis plus the adjusted basis of any direct loans you have made to the corporation. Third-party debt does not count, even if you personally guarantee it. You need an actual outlay from your own funds to build loan basis. Losses beyond basis carry forward indefinitely and become deductible whenever your basis increases, such as through additional contributions or allocated income.7eCFR. 26 CFR 1.1366-2 – Limitations on Deduction of Passthrough Items
Second, the at-risk rules under Section 465 cap your deductible losses at the amount you personally stand to lose. Your at-risk amount generally includes cash contributed, the adjusted basis of contributed property, and borrowings you’re personally liable for or have secured with property not used in the activity.8Internal Revenue Service. Instructions for Form 6198 Nonrecourse debt generally doesn’t increase your at-risk amount, with an exception for certain qualified nonrecourse financing on real estate. Losses blocked here carry forward and become deductible in any future year when your at-risk amount rises enough to absorb them.
What Happens at Death or by Gift
If a taxpayer dies with suspended passive losses, those losses don’t carry over to the estate or heirs. They are deductible on the decedent’s final return only to the extent they exceed the step-up in basis the estate receives.5Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited If a taxpayer dies with $50,000 of suspended passive losses on a rental and the estate gets a $35,000 step-up, only $15,000 is deductible on the final return. If the step-up equals or exceeds the suspended amount, nothing is deductible.
Giving the activity away is worse for the donor. Suspended losses on a gifted passive interest are not deductible; they’re added to the basis of the property immediately before the transfer. The donor gets no deduction, and the recipient inherits the higher basis, which may reduce a future gain or increase a future loss when they sell.
Penalties for Claiming a Deferred Loss Too Early
Deducting a loss that should have been deferred creates an underpayment. The IRS can impose a 20 percent accuracy-related penalty on the portion of the underpayment caused by negligence, disregard of the rules, or a substantial understatement of income tax.9Internal Revenue Service. Accuracy-Related Penalty The penalty comes on top of the tax and interest. Reasonable cause and good faith can excuse it, but that argument is weaker when Form 8949 or a brokerage statement flagged the transaction.
Track every deferred loss you have: the type of rule that suspended it, the amount, the year it originated, and the specific event that will trigger recognition. When that event arrives, the deduction is yours.