You generally cannot claim 401(k) losses on taxes. A drop in your account value from market performance produces no deductible loss, because the money inside a traditional 401(k) hasn’t been taxed yet. The only way a loss becomes deductible is narrow: you take a complete distribution of the entire account, and the amount you receive is less than the after-tax dollars you contributed. Even then, the current tax law and the mechanics of itemizing keep most people from getting any benefit.
Why a Market Drop in Your 401(k) Isn’t Deductible
A traditional 401(k) is a pool of untaxed money. Contributions come out of your paycheck before income tax, employer matches are also pre-tax, and investment gains compound without being taxed each year. The price of that treatment is that a loss inside the account has no tax identity of its own. When the balance falls, all that changes is how much ordinary income you’ll eventually report when you take distributions.
A regular brokerage account works differently. You buy with dollars you’ve already paid tax on, and when you sell at a loss you can offset capital gains and up to $3,000 of other income each year.1Office of the Law Revision Counsel. 26 U.S. Code 1211 – Limitation on Capital Losses That mechanism exists because you paid tax on the money going in. Nothing analogous applies to a pre-tax 401(k).
When you eventually withdraw, the distribution is ordinary income, not a capital gain or loss. There is no Schedule D entry for a 401(k). The money shows up on your return like wages.
The One Situation That Creates a Deductible Loss
A deduction is possible only when the account holds after-tax money and its total value has dropped below that after-tax amount. Two conditions have to line up.
First, you must take a complete distribution of the entire account. Partial withdrawals don’t qualify. This usually happens when you leave a job, the employer terminates the plan, or you cash out the whole balance.
Second, what you receive has to be less than your after-tax basis. Your basis is the total of any contributions made with money that was already taxed. Roth 401(k) contributions are the most common source, since they come from post-tax income. Some plans also allow voluntary after-tax (non-Roth) contributions, which count as basis too. Pre-tax deferrals and employer matches do not, because those dollars have never been taxed.2Internal Revenue Service. What if My 401(k) Drops in Value
An example. You contributed $15,000 in Roth 401(k) deferrals over several years. You leave your job and cash out the entire account, but it’s worth $12,000. The $3,000 shortfall is a non-recoverable basis loss. That’s $3,000 of already-taxed money you’ll never see again.
Your plan administrator will report the distribution on Form 1099-R, showing both the gross amount and the taxable portion.3Internal Revenue Service. Instructions for Forms 1099-R and 5498 Keep it, along with your own records of after-tax contributions. Proving basis is on you.
How the Deduction Works — and Why It Rarely Delivers
If you qualify, the loss is claimed as a miscellaneous itemized deduction on Schedule A.4Internal Revenue Service. Publication 529 – Miscellaneous Deductions That category is where the practical problems start.
For tax years 2018 through 2025, the Tax Cuts and Jobs Act suspended all miscellaneous itemized deductions.5Thomson Reuters Tax & Accounting. Regs Will Clarify Effect of Suspension of Miscellaneous Itemized Deductions on Trusts and Estates During those years the 401(k) basis loss is simply not deductible, period, no matter the numbers.
Beginning in 2026, the suspension is set to expire and miscellaneous itemized deductions come back, but with a 2% floor: only the portion of the loss that exceeds 2% of your adjusted gross income counts. On a $100,000 AGI with a $3,000 non-recoverable basis loss, the first $2,000 is stripped out and only $1,000 remains.
Then you have to itemize at all. Your total itemized deductions, including whatever’s left of this loss after the 2% floor, need to top the standard deduction. The standard deduction for 2026 is projected at $16,100 for single filers and $32,200 for joint filers. If mortgage interest, state and local taxes, charitable gifts, and this loss don’t clear that number combined, the deduction produces nothing.
Stack it all up — full distribution, after-tax basis, an account below that basis, the 2% floor, and the standard deduction hurdle — and the tax break is one very few people ever actually use.
Rolling Over Eliminates the Loss
If you roll the balance into an IRA or a new employer’s 401(k), you give up the loss deduction.2Internal Revenue Service. What if My 401(k) Drops in Value The rollover carries your basis into the new account, and for tax purposes no distribution has been received. Nothing has been realized because the money is still inside a tax-advantaged wrapper.
That creates a real tension when you leave a job with a shrunken account. Rolling to an IRA is usually the sensible move: you keep the tax-deferred growth and avoid the 10% early withdrawal penalty if you’re under 59½. Rolling over also permanently ends any chance at the loss deduction. For most people the rollover still wins, because the deduction is so hard to actually claim. But if your after-tax basis clearly exceeds the account value and you’re already itemizing well above the standard deduction, run the numbers before signing the rollover paperwork.
When an account holds both pre-tax and after-tax money, the IRS applies a pro rata rule to any distribution, so you can’t cleanly separate the after-tax slice on your own. Splitting a full distribution between destinations at the same time is possible under IRS Notice 2014-54, but any after-tax money you send to a Roth IRA has been rolled over, and the loss deduction is gone.6Internal Revenue Service. Rollovers of After-Tax Contributions in Retirement Plans To preserve the deduction, the full balance has to come out as cash, with no rollover.
Employer Stock: A Different Route to a Real Loss
If your 401(k) holds shares of your employer’s company, a separate set of rules can help. Under the net unrealized appreciation (NUA) strategy, you can distribute company stock in-kind into a taxable brokerage account instead of selling it inside the plan. Ordinary income tax then applies only to the stock’s original cost basis inside the plan, not its current market value.
If the stock has fallen below that cost basis, distributing it in-kind and then selling it in the brokerage account produces a capital loss on the taxable side. A capital loss is far more usable than a miscellaneous itemized deduction: it offsets capital gains dollar-for-dollar, then up to $3,000 of ordinary income a year, with any unused amount carrying forward indefinitely.7Internal Revenue Service. Topic No. 409, Capital Gains and Losses
NUA requires a lump-sum distribution — the whole account in a single tax year — and a triggering event such as separation from service, reaching 59½, disability, or death. It applies only to actual employer stock inside the plan, not mutual funds or other investments. Narrow, but when it fits, it produces a tax benefit that the standard basis-loss route rarely delivers.
Losses From Fraud or Plan Mismanagement
A 401(k) that loses money because an administrator embezzled funds or breached a fiduciary duty is a different problem. These situations fall under the Employee Retirement Income Security Act (ERISA), which imposes fiduciary standards on the people who manage retirement plans. The priority is recovering the money, not chasing a tax deduction.
You can file a complaint with the Department of Labor’s Employee Benefits Security Administration, which investigates fiduciary breaches and can pursue legal action on behalf of participants. You can also bring a private ERISA lawsuit.
The tax side is thin. A theft loss deduction still exists in the code, but the Tax Cuts and Jobs Act limited personal theft loss deductions to losses from federally declared disasters for 2018 through 2025.8Internal Revenue Service. Publication 547 – Casualties, Disasters, and Thefts Embezzlement from a retirement plan doesn’t qualify. Starting in 2026, the broader theft loss rules return, but the deduction is available only for losses that aren’t compensated by insurance or legal recovery, and it’s subject to a $100-per-event floor and a 10% AGI threshold.9Internal Revenue Service. Topic No. 515 – Casualty, Disaster, and Theft Losses In almost every fraud case, pursuing the funds through DOL or an ERISA claim will do more for you than the tax code will.