Find the wash-sale candidates hiding in your 1099-B.
Upload your broker's .csv export or Form 8949 data. I'll total your proceeds, cost basis and net gain/loss, then flag every loss where the same symbol was bought again within 30 days — the classic wash-sale pattern. It's a first pass, not the final word: I'm honest about exactly what a single file can't show you, further down.
Most brokers offer a “Download CSV” on the Gains & Losses / Realized gains page. Column headers can be anything — I'll try to map them, and let you fix it if I'm wrong.
Your file is processed entirely in your browser. Nothing is uploaded or stored. It's read with the browser's FileReader and parsed in JavaScript on your own machine. I never see it.
Tell me which column is which, then run it. I've pre-selected my best guesses.
That's a lot of flagged activity for one file. If you trade actively, check whether trader tax status applies to you — it changes how all of this is treated.
- One file only. I can read the single 1099-B/8949 you upload. I can't see your IRA, your other brokerages, or a spouse's accounts — and neither can this tool.
- Cross-account wash sales are invisible here — and on every 1099. If you sold at a loss in one account and re-bought in another, that disallowance appears on no single 1099. This tool can't detect it. That gap is exactly the work I do by hand.
- “Substantially identical” is simplified to an exact symbol/description match. Different share classes, and options on the same underlying, aren't resolved.
- Options and crypto edge cases are flagged, not resolved. Contract-level wash sales and per-wallet crypto basis need the real reconciliation, not a headers-and-dates pass.
- The disallowed figure is an estimate. It's a rough sum of the flagged lots' losses — not a lot-by-lot §1091 basis adjustment.
Trading across multiple brokers or wallets? The disallowances you can't see are exactly what I reconcile.
This is an educational estimate produced in your browser, not tax advice, and it does not create a client relationship. A flag here is a candidate to investigate, not a confirmed wash sale. For your actual situation, book a consult.