Wash Sale Alert
Check same ticker purchases within 30 days of an entered loss sale. See matched shares, estimated loss allocated, and the related replacement basis increase.
How It Works
Enter the ticker, trade date, direction, total amount, share quantity, and cost basis. For a sale, enter total proceeds and the total basis of the shares sold. For a purchase, the total amount is its purchase cost and is used as basis.
Only a sale with total basis above total proceeds has a loss to match. The calculator checks the same ticker within the inclusive 30 calendar day window, then sorts eligible purchases by date and transaction ID for consistent share allocation.
Loss sales are processed by date and ID. Each eligible purchase lot has a limited share quantity that is consumed once across loss sales. A partial match allocates only the per share loss for the shares matched; the total cannot exceed the sale loss.
Use the result as a list of same ticker candidates for review. Purchases before a loss sale count only if the shares were still held after the sale, which this screen cannot verify.
Step by step
- Enter a loss sale and replacement purchase with their total amounts and share quantities.
- Review matched shares, estimated loss allocated, and the replacement basis increase.
- Check the dates and quantities against complete account records before relying on a match.
Worked example
Enter a sale of 100 shares for $900 with a total cost basis of $1,000 on January 15, then a purchase of 50 shares for $500 of AAPL on January 20. The sale loss is $100, or $1 per share.
The calculator matches 50 shares, assigns $50 of the loss to them, and shows a $50 replacement basis increase. The other $50 of loss is not matched by these entered purchases. This example is a screening calculation, not tax advice.
When to use this calculator
Use this screen to compare entered share quantities and dates around a loss sale of a specific ticker.
It can organize exact ticker candidates from the transactions you enter. Confirm the complete lot history and tax treatment before using the estimate on a return.
Common mistakes
Using a loss amount without the sale share count and total basis cannot establish loss per share. Complete the sale proceeds, total basis, and shares before interpreting the estimated allocation.
A prior purchase in the 30 day window may not qualify if those shares were sold before the loss sale. This calculator does not reconcile purchases and sales into complete tax lots.
The Formula
For each loss sale, loss per share = (total cost basis − total proceeds) ÷ shares sold.
For each exact ticker purchase within 30 calendar days before or after: matched shares = min(remaining sale shares, remaining purchase shares).
Loss allocated = matched shares × loss per share.
Replacement basis increase = loss allocated.
The 30 calendar day window includes both boundary dates. Dates are read as UTC calendar dates. Purchases before a loss sale may require confirmation that the shares remained held after the sale.
Limitations and assumptions
This is a limited screen for entered transactions with the same exact ticker. It does not identify substantially identical securities, trades in other accounts or a spouse account, whether prior purchases were held after the loss sale, or later sales and basis chains. A flagged match is not a tax determination, and no match is not a guarantee that the tax rule does not apply.
Key terms
- Same ticker match
- A candidate purchase with the same ticker within 30 calendar days before or after an entered loss sale.
- Matched shares
- The lesser of the loss sale shares still unmatched and the eligible purchase shares still unmatched.
- Loss allocated
- The loss per share multiplied by matched shares. This is the estimated basis increase for those replacement shares.
Compare alternatives
Compare a loss sale with replacement purchases of the same ticker entered here. The Tax Harvest Planner can help review a separate tax scenario, while Capital Gains Tax estimates tax on entered gains.
This screen matches share quantities and estimates the loss allocated to matched purchases. A match is a review flag, not a tax determination. It checks only the entered ticker and trades.
FAQ
What does this wash sale alert check?
Under United States rules, a loss sale may be affected when the same or a substantially identical security is acquired within 30 days before or after the sale. This screen flags potential matches only when the entered tickers match, then allocates the entered loss across matched shares.
What values should I enter?
Enter each trade date, exact ticker, direction, share quantity, and total transaction amount. For a sale, amount means total proceeds and total cost basis is required. For a purchase, amount is total purchase cost and is used as its basis.
How is the disallowed loss estimated?
The sale loss per share is total cost basis minus total proceeds, divided by shares sold. The calculator allocates that amount only to eligible replacement shares, never beyond the sale quantity or remaining purchase quantity. Each purchase share can be matched once.
Are purchases before the loss sale always counted?
No. A purchase in the prior 30 days generally must still be held after the loss sale to qualify. This screen does not track whether those shares were sold before or after the loss sale, so review prior purchases carefully.
Does no match mean there is no wash sale?
No. The screen checks exact ticker matches in the transactions entered. It does not check substantially identical securities, other accounts or spouses, or all basis adjustments from later trades. A missing match is not an all clear.
Related Tools
Use Tax Harvest Planner to review a separate loss harvesting scenario and Capital Gains Tax to estimate tax on entered gains. Those tools do not determine wash sale treatment.