Wash Sale Violation Window Checker
Enter your sell date, repurchase date, and realized loss to instantly see if IRS wash sale rules apply — plus the disallowed loss amount and cost basis adjustment.
What Is the Wash Sale Rule?
The wash sale rule (IRC §1091, explained in IRS Publication 550) prevents investors from claiming a tax loss on a security sold at a loss if a "substantially identical" security is purchased within 30 days before or after the sale. The window is 61 days total: 30 days before the sale, the sale date itself, and 30 days after. If you trade within this window, the loss is "disallowed" for that tax year — it is not permanently gone, but deferred via a cost basis increase on the replacement shares.
The rule was designed to prevent investors from selling an asset purely for the tax loss while maintaining economic exposure to that asset. For example, selling 100 shares of Apple at a $5,000 loss on December 20 and repurchasing the same 100 shares on January 5 triggers a wash sale — the $5,000 loss is disallowed and added to the basis of the January shares. Source: IRS Publication 550, Chapter 4. Last updated: May 2026.
How the 61-Day Window Works
| Day Count | Description | Wash Sale? |
|---|---|---|
| -30 to -1 days | Repurchase BEFORE sale date | Yes — violates wash sale rule |
| 0 (sale date) | Same-day repurchase | Yes — violates wash sale rule |
| +1 to +30 days | Repurchase AFTER sale date | Yes — violates wash sale rule |
| +31 days or more | Repurchase well after sale | No — loss is fully deductible |
Disallowed Loss and Basis Adjustment
When a wash sale occurs, the disallowed loss amount is added to the cost basis of the repurchased shares. This means when you eventually sell the replacement shares (without triggering another wash sale), your adjusted basis reduces the taxable gain or increases the deductible loss. The disallowed loss is not lost permanently — it is deferred. However, if the replacement shares are in a tax-advantaged account (IRA, 401k), the basis adjustment cannot be applied, so the loss is permanently forfeited. Always repurchase in the same account type where you took the loss to preserve the basis adjustment. Consult a qualified tax professional for your specific situation.
Frequently Asked Questions
What is the wash sale rule?
The wash sale rule (IRC §1091) disallows a tax loss deduction when you sell a security at a loss and buy a substantially identical security within 30 days before or after the sale. The disallowed loss is added to the cost basis of the repurchased security. Source: IRS Publication 550.
How wide is the wash sale window?
The wash sale window is 61 days total: 30 days before the sale date, the sale date itself, and 30 days after the sale date. A repurchase on any of these 61 days triggers a wash sale.
What happens to my disallowed loss?
The disallowed loss is not permanently lost. It is added to the cost basis of the replacement shares (basis adjustment). When you eventually sell those shares without triggering another wash sale, the adjusted basis reduces your gain or increases your loss at that time.
Does the wash sale rule apply to cryptocurrency?
Under current IRS guidance, cryptocurrency is treated as property, not a security, so the wash sale rule does not currently apply to crypto. However, proposed legislation could extend wash sale rules to digital assets. Always verify current law with a tax professional.
Can I avoid a wash sale by buying in a different account?
No. The wash sale rule applies across all accounts you own or control, including IRAs and spousal accounts. Selling at a loss in a taxable account and repurchasing in an IRA within the window still triggers a wash sale — and the disallowed loss is permanently lost because an IRA cannot hold an adjusted basis.
What counts as a substantially identical security?
Substantially identical includes the same stock, call options on that stock, and single-stock ETFs. Switching from one S&P 500 ETF to a different S&P 500 ETF (e.g., VOO to IVV) is generally considered NOT substantially identical by most practitioners, but the IRS has not issued definitive guidance on broad-market ETF swaps.