Wash Sale Calculator

Agarapu Ramesh — Editor and content reviewer
Reviewed for accuracy Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Aligned with IRS publications and tax law

Determine if your stock trade triggers the IRS Wash Sale Rule, which disallows deducting a loss if you buy a "substantially identical" security within 30 days.

🧮 Check Wash Sale

$
Date you bought similar stock
Did you replace all sold shares?

How It Works

The Wash Sale Rule prevents you from claiming a loss on a security if you buy a "substantially identical" security within 30 days before or after the sale.

The 61-Day Window

The restricted period is 61 days total: the day of the sale, the 30 days before, and the 30 days after.

Consequences

  • You cannot deduct the loss on your current tax return.
  • The disallowed loss is added to the cost basis of the new replacement stock.
  • This defers the tax benefit until you sell the replacement stock.

Use Cases

  • Check whether repurchasing a stock after a loss sale falls within the 30-day wash sale window.
  • Determine the adjusted cost basis for replacement shares after a wash sale is triggered.
  • Plan the timing of tax-loss harvesting trades to avoid the wash sale rule.
  • Verify whether switching between similar ETFs or mutual funds triggers a wash sale.
  • Calculate the deferred loss amount that gets added to replacement share basis.

Assumptions & Limitations

  • The wash sale window is 61 days total: 30 days before, the sale date, and 30 days after the sale.
  • The rule applies to "substantially identical" securities; this tool does not determine substantial identity.
  • Wash sales across different accounts (e.g., taxable and IRA) may still apply but are not modeled here.
  • Partial replacement (buying fewer shares than sold) results in a proportional disallowance, which is simplified in this tool.
  • The disallowed loss is added to the cost basis of the replacement shares, deferring (not eliminating) the tax benefit.
  • This tool provides estimates for educational purposes only and does not constitute tax advice. Consult a qualified tax professional for your specific situation.

What this calculator does

This page turns the visible tax inputs into a planning estimate that can be checked against official forms and records. It is designed for quick comparison, not as a substitute for professional tax advice.

How to use this calculator

  1. Enter the filing status, income, deduction, credit, withholding, and other fields that apply to your situation.
  2. Run the calculator and review the tax estimate, rate, deduction, or planning result shown on the page.
  3. Compare the result with IRS forms, state rules, and your own records before making payment or filing decisions.

Frequently Asked Questions

Wash sale calculator stocks?
Start with the key tax inputs and keep each number easy to verify. For the Wash Sale Calculator, start with sale date, loss amount, replacement purchase dates, shares bought, shares sold, cost basis, and account details. Then use: disallowed loss is added to the basis of the replacement shares, generally preserving the loss for later. If you sell at a $1,200 loss and repurchase substantially identical shares inside the wash sale window, the current loss may be disallowed and added to replacement basis. Read the result as disallowed loss, adjusted basis, and Form 8949 adjustment. The practical window is 61 days: 30 days before, the sale day, and 30 days after.
How to calculate wash sale adjustment?
Build the estimate in order. First gather sale date, loss amount, replacement purchase dates, shares bought, shares sold, cost basis, and account details. Then apply this working formula: disallowed loss is added to the basis of the replacement shares, generally preserving the loss for later. Use the calculator output for disallowed loss, adjusted basis, and Form 8949 adjustment. If you sell at a $1,200 loss and repurchase substantially identical shares inside the wash sale window, the current loss may be disallowed and added to replacement basis. The practical window is 61 days: 30 days before, the sale day, and 30 days after.
Wash sale cost basis calculator?
Use the Wash Sale Calculator with sale date, loss amount, replacement purchase dates, shares bought. The working formula is disallowed loss is added to the basis of the replacement shares, generally preserving the loss for later. If you sell at a $1,200 loss and repurchase substantially identical shares inside the wash sale window, the current loss may be disallowed and added to replacement basis. Check disallowed loss, adjusted basis. The practical window is 61 days: 30 days before, the sale day, and 30 days after.
Does selling and rebuying stock trigger wash sale?
Yes. The main rule is that a wash sale can occur when you sell stock or securities at a loss and buy substantially identical stock or securities within 30 days before or after the sale. In the Wash Sale Calculator, enter sale date, loss amount, replacement purchase dates, shares bought. If you sell at a $1,200 loss and repurchase substantially identical shares inside the wash sale window, the current loss may be disallowed and added to replacement basis. The practical window is 61 days: 30 days before, the sale day, and 30 days after.
Wash sale rule calculator 61 days?
The 61-day wash sale window means 30 days before the sale, the sale date, and 30 days after. Enter the loss sale date, shares sold, loss amount, and any replacement purchases during that full window. If the replacement shares are substantially identical, the current loss is generally disallowed and added to the basis of the replacement shares. That does not erase the loss forever, but it delays when you can use it.
Wash sale loss disallowed calculator?
Start with the key tax inputs and keep each number easy to verify. Enter sale date, loss amount, replacement purchase dates, shares bought, shares sold, cost basis, and account details in the Wash Sale Calculator. A practical formula is: disallowed loss is added to the basis of the replacement shares, generally preserving the loss for later. If you sell at a $1,200 loss and repurchase substantially identical shares inside the wash sale window, the current loss may be disallowed and added to replacement basis. Review disallowed loss, adjusted basis, and Form 8949 adjustment. The practical window is 61 days: 30 days before, the sale day, and 30 days after.
Form 8949 wash sale adjustment calculator?
For Form 8949, the calculator should show the original loss, the disallowed wash sale amount, and the basis adjustment. The common workflow is: enter the sale on Form 8949, use code W for the wash sale adjustment, and add the disallowed loss back as a positive adjustment. The adjusted basis then carries into the replacement shares. Keep the broker statement and your own trade log because Form 1099-B reporting can be incomplete.

Sources & References

Tax laws change frequently. Always verify current rates and thresholds on IRS.gov before making financial decisions.

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