Wash Sale Rule Explained: What Traders Need to Know

The Wash Sale Rule, codified under IRS Section 1091 since 1921, disallows a capital loss deduction when a substantially identical security is purchased within 30 days before or after the date of the loss sale. For active traders, it is one of the most frequently violated tax rules — and one of the least understood, because the loss does not disappear but instead defers in ways that can trigger a surprise tax bill months later.

Who This Applies To

The wash sale rule applies to any US taxpayer trading stocks, bonds, options, or ETFs in a taxable brokerage account. There are no exemptions based on account size, trading frequency, or trader tax status. The rule does not apply to cryptocurrency (as of 2025), which is not classified as a “security” under Section 1091.

The traders most at risk are those running year-end tax-loss harvesting strategies between October and December, and active day traders who repeatedly enter and exit the same symbols. A TSLA scalper who closes 40 losing positions in November and re-enters within days can accumulate substantial disallowed losses without any immediate warning from their broker.

There are no dollar-amount thresholds. A single wash sale on a 10-share position triggers the same mechanics as one on a 10,000-share position.

Key Rules

61-Day Blackout Window

The window is wider than most traders realize: 30 days before the loss sale, the day of the sale itself, and 30 days after — 61 total calendar days. Purchasing the same stock on day 29 before the sale also disallows the loss retroactively. This means tax-loss harvesting decisions must be made at least 31 days before any planned repurchase.

Loss Is Deferred, Not Destroyed

The disallowed loss is added to the cost basis of the replacement shares, not eliminated. This defers the tax benefit to the eventual sale of those replacement shares. The mechanics matter: if the deferral pushes the gain into a higher-income year, or into short-term capital gains territory instead of long-term, the effective tax cost is higher than the original loss would have been.

All Accounts Are In Scope

The rule applies across all accounts you and your spouse control: taxable brokerage, traditional IRA, Roth IRA, and accounts at other brokers. Selling AAPL at a loss on March 15 in your Fidelity account while your spouse buys AAPL in her Vanguard Roth IRA on March 20 disallows your loss. Worse, in the IRA case the deferred loss is permanently forfeited — IRAs don’t generate taxable losses on exit, so the cost basis adjustment never benefits you.

Options Trigger the Rule

A call option on the same underlying stock is considered substantially identical if it gives the right to acquire the same shares. Selling NVDA at a loss and buying a deep in-the-money NVDA call within 30 days triggers a wash sale. Out-of-the-money calls on the same ticker may also qualify depending on facts and circumstances — this is an area where professional guidance matters.

Crypto Is Currently Exempt

As of 2025, the IRS has not extended Section 1091 to cryptocurrency. Bitcoin, Ethereum, and other crypto assets can be sold at a loss and immediately repurchased without triggering wash sale rules. This makes aggressive tax-loss harvesting viable in crypto portfolios in a way it is not for stocks. Proposed legislation in recent Congresses has sought to extend the rule to crypto — check current law before relying on this exemption.

ETF Substitution Is a Gray Area

Selling SPY at a loss and immediately buying VOO or IVV — all of which track the S&P 500 — is a common tax-loss harvesting technique. The IRS has not ruled these ETFs “substantially identical,” and most tax advisors treat them as safe substitutes. However, the question is unresolved. Switching between S&P 500 ETFs and a total-market ETF (e.g., VTI) provides more separation and is generally considered lower risk.

Practical Examples

Scenario 1 — The Classic Deferral Trap

A trader buys 100 shares of NVDA at $120 on November 15, 2025. The stock drops to $105 and they sell on December 1 to harvest a $1,500 loss for tax year 2025. Nine days later, on December 10, NVDA drops to $98 and they buy back in.

Result: the $1,500 loss is disallowed. The new cost basis becomes $98 + $15 deferred loss per share = $113 per share. If they sell at $130 in March 2026, the taxable gain is $17/share rather than $32/share — the loss wasn’t permanent, just deferred. But the deferral costs money if March 2026 falls in a higher-income year or if the gain is short-term.

Scenario 2 — The Cross-Account Violation

A trader sells AAPL at a $2,000 loss on March 15 in their Fidelity taxable account. Their spouse purchases AAPL on March 20 in a Vanguard Roth IRA. The $2,000 loss is disallowed. Fidelity’s 1099-B will not flag this — the cross-account tracking is entirely the trader’s responsibility. Because the replacement shares are in a Roth IRA, the cost basis adjustment produces no future tax benefit. The loss is permanently forfeited.

Scenario 3 — Active Trader Accumulation

A day trader scalps TSLA throughout November and December, entering and exiting the same ticker 30 times. Many trades are small losses of $200-$500. Because they re-enter within days on nearly every cycle, most of these losses are disallowed under the wash sale rule. By February, when the 1099-B arrives, total disallowed losses for the year reach $18,000 — on a year the trader believed was approximately breakeven.

How JournalPlus Helps with Compliance

JournalPlus logs every trade with precise timestamps and automatically flags positions that fall within the 61-day wash sale window for the same ticker. Traders who log all their accounts — including spouse accounts — into a single JournalPlus workspace get cross-account wash sale visibility that broker statements do not provide.

The platform calculates adjusted cost basis in real time, reflecting deferred wash sale losses so that P&L displayed in the journal matches what will appear at tax time, not just the raw trade math. This prevents the “profitable on paper, surprise tax bill in April” problem that catches active traders off guard.

At year-end, JournalPlus exports a tax summary that itemizes wash sale disallowances by ticker, making it straightforward to reconcile against Form 1099-B Box 1g and hand off accurate records to a CPA. For traders running tax-loss harvesting strategies, this level of tracking is the difference between a strategy that works and one that creates compliance exposure. See also: options tax treatment and trading taxes overview.

Disclaimer

This content is for educational purposes only and does not constitute legal, tax, or financial advice. Tax laws and trading regulations change frequently. The wash sale rule involves complex facts-and-circumstances determinations. Consult a qualified tax professional or CPA for advice specific to your trading situation and account structure.

Frequently Asked Questions

Does the wash sale rule apply to IRAs?

Yes. If you sell a stock at a loss in a taxable account and repurchase it in an IRA or Roth IRA within 30 days, the loss is disallowed. Unlike a taxable account repurchase — where the deferred loss adjusts cost basis and eventually benefits you — the IRA case is worse: the adjusted cost basis inside a retirement account produces no taxable loss on exit, so the deferred loss is permanently forfeited.

Does the wash sale rule apply to cryptocurrency?

As of 2025, the IRS has not classified cryptocurrency as a “security” under Section 1091, so the wash sale rule does not currently apply to crypto. Traders can sell Bitcoin or Ethereum at a loss and immediately repurchase without penalty. However, proposed legislation has repeatedly sought to extend the rule to crypto — verify current law before relying on this exemption for a specific tax year.

What counts as a “substantially identical” security?

The IRS applies a facts-and-circumstances test. The same stock or bond is clearly identical. Call options on the same underlying stock are substantially identical. ETFs tracking the same index (e.g., SPY vs. VOO) are generally treated as non-identical by most tax advisors, but the IRS has not issued a definitive ruling, so caution is warranted. See the pattern day trader alternatives page for similar strategy substitution considerations.

How does the wash sale rule affect my cost basis?

The disallowed loss is added to the cost basis of the replacement shares. If you sell at a $15/share loss and immediately repurchase at $98, your adjusted cost basis is $113 per share. This defers the tax benefit to when you ultimately sell the replacement shares — the loss is not destroyed, just postponed. The cost of postponement depends on your tax rate and income in the year the replacement shares are eventually sold.

Do brokers automatically track wash sales across all my accounts?

No. Brokers report wash sales on Form 1099-B Box 1g only for transactions within the same account at the same broker. Cross-account wash sales — including trades at a different broker, in a spousal account, or in an IRA — are your responsibility to identify and report. Failing to self-report cross-account wash sales is a common source of tax underreporting for active traders. See tax reporting forms for traders for a full breakdown of what brokers report versus what traders must track independently.