1099-B doesn't match your wash sales? What to check

A 1099-B wash-sale figure that differs from your own records is common, and it usually means the two count different things. Each broker sees only its own account and only identical securities, while the IRS rule applies across every account you own. This page is the troubleshooting list; the pages it links to cover each piece in full.

Why a broker's number can differ from yours

• One account at a time. A broker must report a wash sale when the sale and the re-buy are both in the same account for covered securities with the same CUSIP; it is permitted but not required to report more (Form 1099-B instructions). A re-buy at another broker usually doesn't appear: no broker is required to report it, and your broker can't see another broker's trades (the cross-account trap).
• Identical securities only. Different CUSIPs are not matched, so a call option bought after selling the stock may be missing even though it can be a wash sale (where the line is).
• IRA purchases. A re-buy in your own IRA is not required to appear on any 1099-B, yet it permanently disallows the loss (Rev. Rul. 2008-5).
• A spouse's accounts. Pub 550 treats a spouse's purchase as yours, and no broker is required to link the two.
• Options and corporate actions. Option contracts, splits, mergers and spin-offs change what counts as the same security and how lots carry over, and a broker's treatment can differ from a simple ticker match. Our checker withholds symbols whose history it cannot reconcile instead of guessing (methodology).
• The broker can report more. Some brokers report beyond the minimum, so box 1g can also be higher than the all-accounts figure for the same shares (what box 1g covers).

What box 1g is, and when code W applies

Box 1g is the wash-sale loss that broker disallowed on the sales it reports. On Form 8949, code W in column (f) marks a sale whose loss is disallowed as a wash sale, with the amount in column (g) as a positive number. When your figure differs from box 1g, the instructions have you enter the correct amount in column (g), and if it is lower than box 1g, attach a statement explaining the difference (code W in detail).

What to check

1. Collect every account's full trade history, all brokers, all IRAs and your spouse's accounts, through 30 days after your last loss sale.
2. For each loss sale, look for a same-ticker purchase in any account within 30 days before or after it, including dividend reinvestments.
3. Match each one to a box 1g amount: does that broker's figure include it, and is it the same dollar amount?
4. Note anything the 1099-B leaves out: another broker, an IRA, a spouse, an option.
5. Carry the result to Form 8949 and your tax software (TurboTax steps), and bring it to a CPA if any item is unclear.

How the free checker and the worksheet help

The free checker reads your brokers' CSV exports in your browser, nothing uploaded, and lists the cross-account and IRA wash sales with their dollar amounts. You can try it on example trades first. Guardian Pro, a paid Form 8949 worksheet, sets the broker's likely figure beside the all-accounts figure for each sale, and the methodology page lists what it cannot reconcile. It is on sale soon; the Guardian Pro page has what we have decided so far.

Not tax advice. Sources: IRS Publication 550 · Form 8949 instructions · Rev. Rul. 2008-5.

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