A short-term capital loss deduction works in a strict order: the loss first cancels out any short-term capital gains you had that year, then offsets long-term gains, and whatever is left reduces your ordinary income by up to $3,000 ($1,500 if you’re married filing separately). Anything beyond that carries forward to future years with no expiration. The size of the tax benefit depends heavily on what else happened in your portfolio that year, because a short-term loss used against a short-term gain is worth more, dollar for dollar, than one used against a long-term gain.
Why the Short-Term Label Matters
The IRS splits capital gains and losses at the one-year mark. Sell an investment you’ve held for one year or less, and the result is short-term. Hold it longer than a year, and it’s long-term. The holding period begins the day after you buy and runs through the day you sell.
That line matters because gains on each side are taxed at different rates. Long-term gains get preferential rates of 0%, 15%, or 20% depending on your taxable income.1Internal Revenue Service. Topic No. 409, Capital Gains and Losses Short-term gains are taxed as ordinary income, which can run as high as 37%. So a short-term loss that erases a short-term gain is doing heavier lifting than the same loss applied against a long-term gain taxed at 15%. The dollars offset are identical; the taxes saved are not.
How Losses and Gains Are Netted
You can’t simply pool all your gains and losses into one number. The IRS requires a specific sequence that pits same-type figures against each other first, then crosses over.
- Same-type netting comes first. All short-term losses offset all short-term gains. Separately, all long-term losses offset all long-term gains. You end up with a net short-term figure and a net long-term figure, each either a gain or a loss.
- Cross-type netting comes second. If one category shows a net loss and the other a net gain, the loss reduces the gain. A net short-term loss can wipe out a net long-term gain, or vice versa.
What remains after both rounds is your overall capital gain or loss for the year.2Internal Revenue Service. 2025 Instructions for Schedule D (Form 1040)
A Worked Example
Say you have $2,000 in short-term gains and $10,000 in short-term losses, plus $15,000 in long-term gains and $5,000 in long-term losses. Same-type netting leaves you with a net short-term loss of $8,000 and a net long-term gain of $10,000. Cross-type netting then applies the $8,000 short-term loss to the $10,000 long-term gain, leaving $2,000 of net long-term gain as the taxable figure.
Look at what happened. The $8,000 short-term loss ended up canceling long-term gain that would have been taxed at preferential rates. If the picture had been reversed, with a net long-term loss offsetting a net short-term gain, the per-dollar savings would have been larger because short-term gains face higher rates. The ordering isn’t optional, so the mix of what you sold during the year drives the real value of each loss.
The $3,000 Deduction Against Ordinary Income
When total losses exceed total gains after the full netting process, the remaining net capital loss comes off your ordinary income, like wages, salary, and interest. The cap is $3,000 per year for most filers, or $1,500 if you’re married filing separately.1Internal Revenue Service. Topic No. 409, Capital Gains and Losses
The deduction is dollar for dollar up to that cap. A $1,800 net capital loss produces a full $1,800 deduction. A $25,000 net capital loss still produces only $3,000 this year, and the other $22,000 moves to next year.
Three thousand dollars a year is modest against a large loss. An investor sitting on $50,000 of unused losses with no future gains to offset would need close to 17 years to work through the balance. This is why pairing losses with gains in the same year, rather than banking a huge loss with nothing to absorb it, generally produces better results.
Carrying Unused Losses Forward
Any net capital loss above the annual deduction limit carries forward to the following tax year, and it keeps carrying forward until it’s fully used. There’s no expiration.1Internal Revenue Service. Topic No. 409, Capital Gains and Losses
Each carryover keeps its original character. A short-term loss carries over as short-term; a long-term loss carries over as long-term. When they land in the next year, they enter that year’s netting process alongside new gains and losses.3Office of the Law Revision Counsel. 26 U.S. Code 1212 – Capital Loss Carrybacks and Carryovers A short-term carryover will first offset future short-term gains, which is where it does the most good because those gains would otherwise be taxed at ordinary rates.
One wrinkle: the formula for computing the carryover amount treats the $3,000 deduction you claimed as if it were a short-term capital gain, which reduces the short-term carryover before touching the long-term carryover. The result is that your carryover is not simply “net loss minus $3,000.” The Capital Loss Carryover Worksheet in the Schedule D instructions handles the correct calculation.
One boundary worth knowing: capital loss carryovers do not pass to heirs or a surviving spouse. Unused amounts can be claimed only on the final return filed for the year of death, still subject to the $3,000 annual cap. Anything beyond that disappears.
The Wash Sale Rule
The wash sale rule is where planned short-term loss deductions most often collapse. If you sell a security at a loss and buy the same or a substantially identical security within 30 days before or after that sale, the IRS disallows the loss.4Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss From Wash Sales of Stock or Securities
The window runs in both directions. Buying a replacement on Day 1 and selling the original at a loss on Day 15 is a wash sale. Selling at a loss on Day 1 and buying back on Day 25 is also a wash sale. The full restricted period is 61 days: 30 before the sale, the day of the sale, and 30 after.
In most cases the loss isn’t permanently gone. The disallowed amount gets added to the cost basis of the replacement shares, so you recover the tax benefit when you eventually sell those replacement shares in a non-wash transaction.4Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss From Wash Sales of Stock or Securities
Automatic Reinvestments and Cross-Account Purchases
Two situations trip people up. Automatic dividend reinvestment plans can quietly repurchase shares of a fund you just sold at a loss, and if the reinvestment lands inside the 30-day window, the loss is disallowed to that extent.5Internal Revenue Service. Case Study 1: Wash Sales Turn reinvestment off before harvesting a loss.
The rule also reaches across your accounts, including IRAs, and across your spouse’s accounts. Sell a stock at a loss in your taxable account, have your spouse buy the same stock in their IRA within 30 days, and the loss is disallowed. The IRA version is especially harsh because the disallowed loss can’t be added to basis the way it would be in a taxable account, so the deduction can be lost outright rather than deferred. Brokers only track wash sales within a single account and single security identifier, so the cross-account bookkeeping is on you.
Losses That Don’t Qualify
Some losses look deductible but aren’t. Two categories are blocked.
Losses on personal-use property, including your home, your personal vehicle, and household goods, are not deductible.1Internal Revenue Service. Topic No. 409, Capital Gains and Losses The asset must be held for investment or used in a trade or business.
Losses from sales to related parties are also disallowed. That includes siblings, your spouse, parents, and children, as well as corporations or partnerships in which you own more than 50% of the value.6Office of the Law Revision Counsel. 26 U.S. Code 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers You can’t create a deduction by shifting the asset to someone you’re close to.
Reporting the Deduction
Two forms carry the work. Form 8949 lists each sale individually, with acquisition date, sale date, proceeds, and cost basis, split into short-term and long-term sections. Those totals feed Schedule D, which runs the netting and produces the final figure.7Internal Revenue Service. Instructions for Form 8949 (2025)
If Schedule D line 16 shows a loss, the form limits your deduction to the lesser of that loss or $3,000 ($1,500 for married filing separately). The capped number flows to Form 1040, line 7a.8Internal Revenue Service. 2025 Schedule D (Form 1040) If anything is left over, the Capital Loss Carryover Worksheet in the Schedule D instructions tells you how much short-term and long-term loss to carry into the next year.
A reporting note on basis: brokers report cost basis to the IRS for “covered” securities, generally those acquired after specific dates that vary by asset type. For noncovered securities bought earlier, the broker reports basis only to you, and the figure on your Form 8949 has to come from your own records. Wrong basis is one of the easier ways to understate or overstate a legitimate short-term loss.
A Bonus for Higher Earners: The 3.8% NIIT
Taxpayers above $200,000 of modified adjusted gross income single, or $250,000 married filing jointly, pay an additional 3.8% Net Investment Income Tax on investment income, including capital gains.9Internal Revenue Service. Questions and Answers on the Net Investment Income Tax Those thresholds don’t adjust for inflation, so they catch more filers each year. Capital losses reduce net investment income, which can shrink or eliminate the surtax. For someone near the threshold, a short-term loss can save ordinary income tax on the gain it offsets plus the 3.8% on top.