The Wash Sale Rule in 2026 — When the IRS Disallows an Investment Loss, and the IRA Trap That Makes It Permanent
Realizing a loss on an investment is one of the few ways to turn a market decline into a tax benefit, and the wash sale rule exists to stop investors from claiming that benefit while keeping the same position. Internal Revenue Code Section 1091 disallows the loss when a taxpayer sells a security at a loss and acquires a substantially identical one within a narrow window. The rule is simple to state and easy to trip over in practice, particularly across multiple accounts. Here is how it works under IRS rules.
What Counts as a Wash Sale?
Per IRS Publication 550, a wash sale occurs when a taxpayer sells or otherwise disposes of stock or securities at a loss and, within 30 days before or after the sale, buys substantially identical stock or securities, acquires them in a fully taxable trade, enters into a contract or option to acquire them, or acquires them for an IRA or Roth IRA. The window therefore covers 61 days: the day of the sale, the 30 days before, and the 30 days after. The rule reaches stock, bonds, options, and contracts to buy or sell such securities, and it does not reset at the calendar year boundary, so a sale in December and a repurchase in January can still be a wash sale.
What Happens to the Disallowed Loss?
In the ordinary case the loss is deferred rather than eliminated. Under Section 1091(d), the disallowed loss is added to the cost basis of the replacement shares, and the holding period of the original shares carries over to them. The tax benefit is recovered when the replacement shares are eventually sold in a transaction that is not itself a wash sale. This is why a wash sale is an issue of timing in most cases, and why the basis on the replacement shares should be tracked carefully.
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The IRA Trap
The most costly version involves retirement accounts. Revenue Ruling 2008-5 addresses an individual who sells stock at a loss in a taxable account and causes an IRA or Roth IRA to purchase substantially identical stock within the 30-day window. The ruling holds that the loss is disallowed under Section 1091, and that the individual's basis in the IRA or Roth IRA is not increased by the disallowed loss. Because the loss never moves into a basis that can be recovered, it is effectively lost permanently. This applies even though the IRA is a separate account, so a purchase made automatically inside a retirement account can undo a loss harvested in a taxable one.
Accounts and People the Rule Reaches
The rule is applied to the taxpayer, not to a single account, so a sale in one brokerage account and a purchase in another can trigger it. Brokers report wash sales on Form 1099-B, and the amounts flow to Form 8949, but generally only for identical securities within the same account, so a wash sale across accounts or custodians may not appear on the statement and still applies. Automatic dividend reinvestment is a frequent unintended trigger, because shares bought through reinvestment within the window count as acquisitions. A purchase by a spouse can also be treated as a purchase by the taxpayer for this purpose.
Reporting and Where It Fits in Loss Planning
A wash sale is reported on Form 8949, the form used for sales of capital assets, with code W in column (f) and the disallowed loss entered as a positive adjustment in column (g). The rule is a core constraint on tax loss harvesting, the strategy we describe in our guide to tax loss harvesting, and it determines which losses become the capital loss carryovers covered in our guide to capital loss carryovers. A loss that is disallowed never reaches the capital loss carryover calculation until it is recovered through the basis adjustment.
How Tax Wealth Consultant Approaches the Wash Sale Rule
Tax Wealth Consultant reviews activity across every account a client controls, including retirement accounts and dividend reinvestment settings, before a loss is harvested, and tracks the basis adjustment on replacement shares so a deferred loss is recovered when it should be, which is part of ongoing tax loss harvesting and tax planning. A harvested loss is only worth something if it survives the wash sale rule, and that tax planning question is one to answer before the trade, not after.
A harvested loss only counts if it survives the wash sale rule. Check before you trade.
Schedule your confidential 30-minute review with Tax Wealth Consultant today.
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Tax Wealth Consultant provides tax planning, tax preparation, and wealth advisory services for business owners, professionals, and investors in Irvine, Orange County, and beyond.
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