Wash Sale Calculator for Stocks and Options CSVs

How the wash sale CSV checker works

The wash sale rule prevents you from claiming a tax loss when you sell a security at a loss and then buy back the same (or a substantially identical) security within a short window. This tool lets you upload trade history exports from one or more brokerages, combines and standardizes them, and then scans for possible wash sales you might otherwise miss — especially across multiple accounts.

What is a wash sale?

A wash sale occurs when you sell a stock, ETF, or option at a loss and acquire a substantially identical position within 30 days before or after the sale. The IRS disallows the loss for that tax year. Instead of disappearing, the disallowed loss is added to the cost basis of your replacement shares, which defers the benefit until you eventually sell them in a non-wash transaction.

Why 30 days before and after matters

The wash sale window spans 30 calendar days before and 30 calendar days after your loss sale — a 61-day window that includes the sale date itself. It uses calendar days, not trading days, so weekends and holidays count. A replacement purchase anywhere in that window can trigger the rule, which is why timing your buy-backs carefully matters.

Why multiple broker accounts cause blind spots

Your broker tracks wash sales within its own walls and reports them on your Form 1099-B. But the rule applies to you, across every account you control. If you sell at a loss in Robinhood and rebuy in Fidelity, Schwab, or Webull — or in a spouse's account — neither broker nets the wash sale. Combining CSVs from all your accounts is the only way to catch these cross-account matches.

Why IRA and Roth IRA purchases can matter

A loss sale in a taxable account followed by buying the same security in your IRA or Roth IRA can trigger a wash sale — and unlike a normal wash sale, the disallowed loss generally cannot be added to the IRA's basis, so the loss may be permanently lost. Label your account types in the tool so it can warn you about these scenarios; then confirm the treatment with a tax professional.

Why options can be complicated

Options add several wrinkles. Buying a call option on a stock you just sold at a loss can be treated as acquiring a substantially identical position. Closing an option at a loss and reopening the same contract is a more clear-cut wash sale. But options with different strikes or expirations on the same underlying are a gray area. This tool tiers option findings into high confidence (exact contract), medium (stock-to-call), and needs review (same underlying, different contract).

Why CSV data quality matters

The accuracy of any wash sale estimate depends on your data. If your export lacks a realized gain/loss column, the tool estimates it from proceeds minus cost basis. If neither is present, those rows are flagged as insufficient data and skipped rather than guessed. Including cost basis, proceeds, and clear action/date/symbol columns produces the most complete results.

What StockLeo can and cannot detect

This tool can help you spot same-account, cross-account, IRA/Roth, and many option-related possible wash sales, estimate the disallowed loss, and surface possible safe-to-buy-back dates. It cannot guarantee complete or tax-ready results, definitively rule on "substantially identical" securities, handle short sales perfectly, account for every broker quirk, or replace professional judgment. Treat every result as a prompt to investigate, not a final answer.

How to use the exported report with a CPA or tax software

Export the matched-events CSV, summary CSV, or printable report and bring it to your CPA or compare it against your broker's 1099-B. The report shows each possible loss sale, its replacement purchase, the matched quantity, and the estimated disallowed loss — a useful starting point for a professional to verify and adjust. Everything is generated locally, so you control where it goes.