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Tax answers · IRC §1091

When Does A Wash Sale Prevent A Stock-Loss Deduction?

THE TAX CUTTERY® · From the practice of Paul D. Diaz, EA, MBA
Updated September 26, 2026 · Federal tax overview

A wash sale can disallow a loss when you sell stock or securities at a loss and acquire substantially identical stock or securities within 30 days before or after the sale. The window crosses calendar years. A December sale does not become safe merely because the replacement purchase occurs in January.

Review Purchases As Well As Sales

The rule can involve purchases made before the loss sale. Automatic dividend reinvestment, recurring investments, and activity in other accounts can matter. A single brokerage statement may not describe every transaction relevant to your return.

Understand Where The Disallowed Loss Goes

In a typical taxable-account wash sale, the disallowed loss is added to the replacement security’s basis, affecting a later sale. Different treatment can apply when the replacement is acquired in an IRA. Do not assume every disallowed loss is available to deduct next year.

Coordinate Records Before Tax-Loss Harvesting

Review the security, dates, quantities, and accounts involved before deciding how a proposed sale will be reported. A tax objective should be considered alongside your investment objectives; this explanation does not recommend a purchase or sale.

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Source And Scope

IRS Publication 550 — Investment Income and Expenses. Use the rules and instructions for the tax year involved. This overview does not cover every exception and is general information, not a conclusion about a particular return.

Continue in the Guide: Chapter 24.

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