US Wash Sale & Cost Basis Tracker

Determine if your recent stock purchase triggered an IRS Wash Sale and calculate your new adjusted cost basis.

Transaction History

Step 1: The Loss Sale

Original Buy Price ($)

Sale Price ($)

Sale Date

Step 2: The Re-Buy

New Buy Price ($)

New Buy Date

Quantity (Shares)

Wash Sale Detected

Disallowed Loss

Rule Triggered: Buy within 0 days

$200.00

Total Realized Loss

IRS Impact

Loss Disallowed

Cannot use this loss to reduce taxes this year.

Adjusted Cost Basis

$105.00 / share

Loss added to your new cost basis.

Tax Filing Summary

Total Shares Involved10

Days Between Trades0 Days

Cost Basis Increase+$200.00

New Total Portfolio Value (Adjusted)$1050.00

The 61-Day Window

A wash sale covers 30 days before, the day of, and 30 days after the sale. If you buy "substantially identical" stock within this window, you cannot claim the loss on your current tax return.

What is the IRS Wash Sale Rule?

The Wash Sale rule (IRS Publication 550) prevents taxpayers from claiming a loss on the sale of a security if they purchase a "substantially identical" security within 30 days before or after the sale.

1. The 61-Day Danger Zone

Many traders mistakenly think the rule only applies 30 days after a sale. In reality, the window is 61 days: 30 days before the sale, the day of the sale, and 30 days after the sale.

2. Disallowed Losses

If a wash sale is triggered, you cannot use the loss to offset your capital gains or income for the current tax year. Instead, the "disallowed loss" is added to the cost basis of the new shares you purchased.

3. Adjusted Cost Basis

The benefit of a wash sale is that your loss isn't gone forever; it's deferred. By adding the loss to the cost basis of the new shares, you will eventually realize that loss when you sell the new shares (as long as you don't trigger another wash sale).

Example of a Wash Sale

You buy 100 shares of Apple at $150 and sell at $120 (a $3,000 loss). Two weeks later, you buy Apple again at $125. Because you bought back within 30 days, your $3,000 loss is disallowed. Your new cost basis for the $125 shares becomes $155 ($125 + $30 loss per share).

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