Wash Sale Rule Explained: The 61‑Day Window Every Investor Should Understand

What is the Wash Sale Rule?

The wash sale rule is codified in Internal Revenue Code Section 1091. It provides that a taxpayer may not deduct a loss from the sale or other disposition of shares of stock or securities if, within a period beginning 30 days before the date of that sale and ending 30 days after the sale, the taxpayer acquired — or entered into a contract to acquire — substantially identical stock or securities.

In plain terms: if you sell an investment at a loss and quickly buy the same thing back, the IRS treats the transaction as a round-trip that never really changed your economic position. The loss is therefore disallowed for the current tax year. The term "wash sale" captures the idea that the transaction effectively washes out — nothing economically meaningful changed.

Congress enacted this rule to prevent investors from generating artificial tax losses while maintaining their investment position. Without it, an investor could sell a losing position on December 31, immediately repurchase the same shares on January 1, and claim the tax loss — all while holding the exact same economic position throughout.

The 61-Day Window Explained

The wash sale rule is often summarized as a "30-day rule," but this description understates the actual window. The full restriction spans 61 days:

• The 30 days before the sale date
• The sale date itself
• The 30 days after the sale date

This means the prohibited period is not simply "wait 30 days after selling." Purchasing the same security even a few weeks before you plan to harvest a loss will trigger a wash sale. The rule looks backward as well as forward.

Why the Window Matters for Tax-Loss Harvesting

Investors who practice tax-loss harvesting need to be aware of both directions of the window. If you automatically reinvest dividends in a fund and then attempt to harvest a loss in the same fund, the dividend reinvestment purchase — which occurred within 30 days before the sale — will trigger a wash sale on at least a portion of your sold shares. Dividend reinvestment plans (DRIPs) are a common and overlooked source of inadvertent wash sales.

The safe approach: to fully claim a harvested loss, you must ensure that no purchase of substantially identical securities occurs at any point within the 61-day window centered on the sale date. Practically, many tax professionals recommend waiting at least 31 days after the sale before repurchasing the same security, and confirming no purchases occurred in the 30 days leading up to the sale.

Days are counted using calendar days, not trading days. Weekends and holidays count. The sale date is included in the count.

What Counts as Substantially Identical?

The IRS has never issued a comprehensive list of what constitutes "substantially identical" securities, leaving considerable ambiguity. However, the following principles are generally accepted based on IRS guidance and Tax Court decisions:

Clearly Substantially Identical

• Selling shares of a company and repurchasing shares of the same company (same ticker)
• Selling a fund and repurchasing the same fund in a different account
• Selling shares and purchasing call options that are "in-the-money" enough to give you nearly equivalent economic exposure to the same shares
• Selling bonds and purchasing bonds that are sufficiently similar in issuer, maturity, and terms

Generally Not Substantially Identical

• Two ETFs that track different but correlated indexes (e.g., S&P 500 vs. total US stock market — though this is not guaranteed; see below)
• Two ETFs from different fund families that track the same index — the IRS has not definitively ruled that these are substantially identical, and many practitioners treat them as acceptable replacements, but there is no certainty
• Preferred stock vs. common stock of the same company (generally different, but depends on conversion features)
• Stocks in different companies in the same industry

Cross-Account Rules (Brokerage + IRA)

One of the most consequential and least-understood aspects of the wash sale rule is that it applies across all accounts you own — not just within a single brokerage account. The IRS looks at the taxpayer, not the account.

Multiple Taxable Accounts

If you sell a stock at a loss in Account A and your spouse or you repurchase the same stock in Account B at another brokerage within the 61-day window, a wash sale has occurred even though the accounts are at different institutions. Brokers only report wash sales within their own systems — they cannot see your other accounts — so the tracking burden falls entirely on you.

The IRA Trap

Repurchasing a substantially identical security inside a traditional IRA or Roth IRA within the 61-day window triggers a wash sale — and the consequences are particularly harsh: the disallowed loss is permanently lost. Unlike wash sales in taxable accounts, where the disallowed loss is added to the replacement shares' cost basis and eventually recovered upon a future sale, there is no mechanism to add to the basis of securities inside an IRA for this purpose. The loss evaporates permanently.

This risk is particularly acute for investors who make regular automatic contributions to IRAs or 401(k)s that hold the same funds present in their taxable accounts. Review your automatic investment schedules when planning to harvest losses.

Spousal Wash Sale Rules

The wash sale rule applies to purchases made by your spouseas well as to purchases made through entities you control, such as a corporation in which you hold a majority interest. This is not always intuitive, but it follows from the IRS's focus on the economic substance of the transaction: if your household maintains the same investment position through a spousal purchase, the wash sale rule applies.

Practically, this means that if you sell a stock at a loss and your spouse buys the same stock within the 61-day window — even in an entirely separate account that your spouse solely owns — the wash sale rule applies to your loss. Coordination between spouses on tax-loss harvesting activities is therefore important.

Married couples who file separately should be particularly careful, as each spouse's account activity can affect the other's tax position through this rule.

What Happens to the Disallowed Loss?

When a loss is disallowed under the wash sale rule in a taxable account, it is not simply erased. Instead, it is added to the cost basis of the replacement shares you purchased. This is called a basis adjustment, and it means the loss is deferred rather than permanently eliminated (in most cases — see the IRA exception above).

In addition to the basis adjustment, the holding period of the replacement shares is adjusted. The holding period of the shares you sold at a loss is tacked on to the holding period of the replacement shares, which can affect whether a future sale of the replacement shares produces a short-term or long-term gain or loss.

How Basis Adjustment Works

Suppose you sell 50 shares of a stock at a $1,000 loss, and the sale is flagged as a wash sale because you repurchased the same stock within the 61-day window. That $1,000 disallowed loss is added to the cost basis of the newly purchased shares. When you eventually sell those replacement shares (without triggering another wash sale), the higher basis reduces your taxable gain or increases your deductible loss by $1,000 — recovering the deferred tax benefit at that time.

The implication: if you never repurchase the security (or repurchase it after the 61-day window closes), you avoid the wash sale entirely and can claim the full loss in the current tax year. The deferral mechanism only applies when you do trigger the rule.

Wash Sales and Options

Options add a layer of complexity to wash sale analysis because both call options and put options can trigger — or be part of — a wash sale transaction.

Call Options as Replacement Securities

If you sell shares at a loss and then buy a call option on the same stock within the 61-day window, the IRS may treat the call option as a substantially identical security — particularly if the option is deep in-the-money and provides near-equivalent economic exposure to owning the shares outright. The threshold is not bright-line, but the general principle is that a contract that gives the right to acquire substantially identical stock can itself be substantially identical.

Selling a Put to Trigger a Wash Sale

Selling a deep-in-the-money put option on the same stock within the 61-day window can also trigger a wash sale, because selling a put creates an obligation to purchase the stock — which the IRS may view as entering into a contract to acquire substantially identical stock. Treasury Regulation 1.1091-1(b) explicitly states that acquiring a contract or option to acquire substantially identical stock triggers the rule.

Options on Related Indexes or Funds

Options on the same ETF or fund you sold are almost certainly substantially identical. Options on a broad index that the fund tracks may also be considered substantially identical in some circumstances. This is an area where the guidance is genuinely unsettled, and the stakes are high enough that consulting a qualified tax professional is strongly recommended before combining options strategies with tax-loss harvesting.

Does the Wash Sale Rule Apply to Crypto?

Under current US federal law as of 2025, cryptocurrency is classified as propertyunder IRS Notice 2014-21, not as a security. Because Section 1091 of the Internal Revenue Code applies specifically to "stock or securities," and the IRS has determined that cryptocurrency does not fall into that category, the wash sale rule does not currently apply to Bitcoin, Ethereum, or other digital assets.

What This Means in Practice

A crypto investor can sell Bitcoin at a loss and immediately repurchase it — even on the same day — and still claim the full tax loss. This has made crypto tax-loss harvesting a more flexible tool than loss harvesting in the stock market, where the 61-day window requires careful timing.

Proposed Legislation

Multiple legislative proposals in recent years have sought to extend wash sale treatment to digital assets. The Lummis-Gillibrand Responsible Financial Innovation Act and several budget proposals from the executive branch have included provisions to close the crypto wash sale exemption. As of the publication date of this article, no such legislation has been enacted into law. However, this is an area of active legislative attention, and the current exemption should not be assumed to be permanent.

Investors who rely on crypto loss harvesting should monitor legislative developments closely and consult a qualified tax professional for current guidance.

Common Mistakes Investors Make

The wash sale rule catches many investors off guard because it operates in ways that are counterintuitive or easy to overlook in the course of normal investing activity.

1. Dividend Reinvestment Plans (DRIPs)

If you have automatic dividend reinvestment enabled on a fund and you attempt to harvest a loss in that fund, the recent dividend reinvestment purchase almost certainly falls within the 30-day look-back window, triggering a wash sale on at least the shares purchased via DRIP. Suspending dividend reinvestment before a planned loss harvest is a common best practice.

2. Automatic 401(k) or IRA Contributions

Regular automatic contributions to a retirement account that purchases the same funds you hold in your taxable brokerage account can trigger cross-account wash sales — potentially with permanent loss disallowance if the retirement account is an IRA.

3. Counting Only 30 Days Forward

Many investors mistakenly believe they only need to wait 30 days after the sale to repurchase. The actual rule requires 31 days of clean separation after the sale (to ensure the 30-day post-sale window is fully clear). Waiting exactly 30 days is not sufficient.

4. Ignoring the 30-Day Look-Back

Buying additional shares of a position within 30 days before harvesting the loss disallows the loss on the shares purchased during that look-back period. Investors who dollar-cost average regularly can inadvertently trigger this.

5. Partial Wash Sales

The wash sale rule applies proportionally when the number of replacement shares purchased is less than the number of shares sold. If you sell 100 shares at a loss and repurchase only 60 shares within the 61-day window, the loss on 60 shares is disallowed while the loss on the remaining 40 shares may be claimed. This partial treatment requires careful tracking.

6. Assuming Year-End Losses Are Always Claimable

Selling a position at a loss on December 31 does not guarantee you can claim the loss. If you repurchased that same security in early January — within 30 days after the sale — the wash sale rule will disallow the loss even though the purchase occurred in the new calendar year.

How Brokers Report Wash Sales (Form 1099-B Box 1g)

US brokers are required to track and report wash sales that occur within their own systems and report them on Form 1099-B. The key field is Box 1g, which reports the dollar amount of any wash sale loss disallowed during the year.

How to Handle Box 1g on Your Tax Return

When preparing your tax return, you report securities sales on IRS Form 8949. For any transaction with a disallowed wash sale loss:

1. Enter the disallowed amount from Box 1g in column (g) of Form 8949
2. Enter adjustment code W in column (f)
3. The disallowed loss is added back to the proceeds, reducing the net loss claimed
4. The totals from Form 8949 flow to Schedule D, which summarizes your overall capital gains and losses

Many tax software programs and tax professionals handle this automatically when you import your 1099-B. However, it is worth reviewing the imported data to ensure all wash sale entries appear correctly — especially if you have accounts at multiple brokerages, since cross-account wash sales will not be reflected in any single 1099-B.

The Limitation of Broker Reporting

Brokers only track wash sales within their own systems. They cannot see your other brokerage accounts, IRA accounts at other institutions, or your spouse's accounts. If a wash sale occurs across accounts at different institutions, it will not appear on any 1099-B — the taxpayer is solely responsible for identifying and correctly reporting it. Failing to do so can constitute an error on your tax return.

For investors with complex portfolios or multiple accounts, working with a qualified tax professional or using specialized portfolio tax software that aggregates activity across all accounts is strongly recommended. See also our guide to capital gains tax reporting for more on Form 8949 and Schedule D.

Worked Examples With Numbers

Example 1: Simple Wash Sale — Loss Disallowed and Deferred

Example 2: Year-End Trap

Example 3: The IRA Trap — Permanent Loss

Example 4: Partial Wash Sale

Example 5: Clean Harvest — No Wash Sale

Frequently Asked Questions