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Wash Sale CalculatorDisallowed Loss and Adjusted Basis (IRC 1091)

What do these figures come to once the work is shown?

Loss disallowed by repurchasing within 30 days, the loss still allowed now and the higher basis of the replacement shares.

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Your figures
Example figuresIllustrative only. Type over them with your own.
Loss disallowed
$900
Added to the basis of the replacement shares
Loss allowed now
$600
Total loss on the sale
$1,500
Drawn to one scale
Loss disallowed$900
Loss allowed now$600
Total loss on the sale$1,500
Basis per replacement share (matched shares)$53
All results
MeasureResult
Loss disallowed$900
Loss allowed now$600
Total loss on the sale$1,500
Basis per replacement share (matched shares)
Replacement price plus the disallowed loss per share
$53
Replacement shares carrying the added basis60.00
How this was worked out
Work shownrecomputed as you type
Loss per share = basis per share - sale price per share
Disallowed = loss per share x lesser of shares sold and replacement shares
New basis = basis of shares sold + (replacement price - sale price)
which equals the replacement price + loss per share

Illustrative arithmetic on the figures you enter. Check the result against your firm's methodology before relying on it.

The formulas

  • Loss per share = basis per share - sale price per share
  • Disallowed = loss per share x lesser of shares sold and replacement shares
  • New basis = basis of shares sold + (replacement price - sale price)
  • which equals the replacement price + loss per share

How it works

Section 1091 denies a loss on stock or securities when you buy substantially identical stock or securities within 30 days before or after the sale. The window covers 61 days in total, centered on the sale. The disallowed loss is not lost for good: it is added to the basis of the replacement shares, so it comes back when you sell them.

Dealers in stock or securities selling in the ordinary course of business are excepted. Which shares are matched when the numbers differ is decided under Treasury regulations, so this tool matches the lesser of the two share counts.

Illustrative figures only. Check the result against your firm's methodology before relying on it.

Common questions

Does a gain trigger the rule?

No. Section 1091 disallows losses only, so this tool shows zero disallowed on a gain.

Does buying in an IRA count?

This tool does not decide that. It applies the statute to the shares you enter.

What are substantially identical securities?

The statute does not define the term in the text read here. This tool leaves that judgment to you.

Sources

Runs in your browser. The figures you type are not sent to CORAA or stored. Check the result against your firm's methodology before relying on it.

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