🔒 Runs in your browser — no signup, no account linking, trades never uploaded
Never eat a wash-sale
surprise again.
Your broker only has to report wash sales inside one account. The IRS counts them across every account you and your spouse own — including IRAs. A cross-account wash isn't required on your 1099-B, so the 1099-B likely shows a clean loss your tax software takes at face value — but that loss was disallowed and folded into the replacement shares' basis, recoverable only when you sell those. If the re-buy landed in an IRA, it's gone for good.
No CSV handy? Try it with example trades: three made-up accounts, nothing to download.
Drop broker CSVs · results in seconds for most files · keeps working offline once the tab is open
Prefer to read first? The year-end wash-sale checklist · All guides · Get the year-end reminders by email
The trap, in one example
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Jul 5 — you harvest a loss
You sell NVDA at a $4,000 loss in your Schwab taxable account. Smart tax-loss harvesting… so far.
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Jul 18 — you re-buy elsewhere
The dip looks juicy, so you buy NVDA back — in your Robinhood account. Or worse, your IRA auto-invests into it. Neither broker warns you. Neither one can see the other.
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February — the 1099 looks clean
Schwab's 1099-B shows the full $4,000 loss, nothing disallowed — it never saw the Robinhood or IRA buy. But the loss is disallowed: it's added to the basis of the new shares, and you get it back only when you finally sell them (and don't wash that sale too). If the re-buy was in your IRA, it's gone forever — no basis adjustment, no do-over. Either way, the adjustment is yours to report (Form 8949, code W).
This is common enough that the IRS wrote a ruling about the IRA version (Rev. Rul. 2008-5). And even a deferred loss can bite at filing time: in a widely reported 2021 case, a Robinhood trader with about $45,000 of profit reportedly faced an estimated $800,000 tax bill, largely from wash sales — per Forbes, an unnamed trader's tax-software estimate, not an IRS assessment.
What Wash-Sale Guardian does
1 · Drop your CSVs
Robinhood, Schwab, Fidelity, IBKR, E*TRADE, tastytrade — or other trade CSVs by mapping their columns (date, ticker, buy/sell, quantity, price); E*TRADE's newer Morgan Stanley layout isn't supported yet. Tag each file taxable or IRA.
2 · See your danger windows
"Don't re-buy NVDA in any account before Aug 5." Live 30-day windows across every account, plus violations you've already incurred, with dollar amounts.
3 · Hand your CPA the summary
Year-end adjusted-basis report per lot — reconcile it against your 1099-Bs before TurboTax takes them at face value.
Why there's no "connect your brokerage" button
Other tools want you to link your accounts through an aggregator. We think handing a startup your brokerage login is exactly backwards. Wash-Sale Guardian parses CSV exports locally in your browser — the checker keeps working offline once its tab is open, and the app page loads zero third-party scripts. Your trades never touch a server: nothing on this site sends them anywhere.
Get the year-end wash-sale reminders
Short emails at the moments that matter: before Nov 30 (the last day to sell at a loss and still re-buy within 2026); before Dec 31; when 1099-Bs arrive in February; and the day Guardian Pro goes on sale. The one-page year-end checklist PDF comes with it.
Sign up and a link to the PDF appears right here. Confirm the email we send and you're on the list: about four to six emails a year, and you can unsubscribe in one click from any of them. Your trades stay in your browser. The form sends Kit only your email address and the page you signed up from (plus a tag naming this form) — nothing else (see Privacy).
Questions traders ask
- Is my trade data uploaded anywhere?
- No. Parsing and analysis run in your browser; the ledger is stored in your browser's local database. Verify it yourself: open DevTools → Network, or switch to airplane mode with the tab open — it keeps working until you close it.
- Do I have to re-upload constantly?
- No — your ledger persists in the browser between visits, and one upload keeps answering "can I re-buy X?" correctly until you trade again in any account — including an IRA auto-invest or dividend reinvestment you didn't think of as a trade. Re-upload after new trades (there's also a 10-second manual entry for a quick patch), and download the one-file ledger backup to move devices.
- What should I be doing before December 31?
- Work the year-end wash-sale checklist: the dates that matter (Nov 30; Dec 31, the last trading day — trade date governs; Dec 31 through January; mid-February 1099-Bs), what to check before and after every harvest sale, and the IRA trap. The guides cover the rule, the cross-account trap, the 61-day window and how to reconcile box 1g in February.
- What does it NOT handle?
- Short positions, cash-settled options, and cross-ticker "substantially identical" calls (SPY vs VOO) are out of scope for now — and the tool tells you loudly when it sees them instead of guessing. It also refuses to give verdicts on symbols with incomplete history.
- Is this tax advice?
- No. It's a conservative early-warning system. For filing decisions, bring the year-end summary to a CPA — that's exactly what it's designed for.