How to Read Form 1099-B for Stock Trades

Go line by line. Every sale on the form gets its own row, and you read each row across: the security in 1a, the purchase and sale dates in 1b and 1c, the money you received in 1d, and what the shares cost you in 1e. After that come the three boxes that change how the sale gets treated. Box 1g holds any loss your broker disallowed under the wash sale rule, box 2 sorts the sale into short term or long term, and box 12 shows whether the IRS got your basis figure or only you did. The rest flag rarer cases or carry state details.

That’s the reading. Checking is the harder half, because the form reports what one broker saw in one account, and some of the things that move your numbers happen where it can’t see them.

Where the 1099-B shows up

You probably won’t get it as a standalone form. Brokers usually send it inside a consolidated 1099 statement, and the 1099-B pages are the ones listing each sale. The deadline for brokers to furnish it is February 15, and when that date falls on a weekend or a holiday, it moves to the next business day, which is how it landed on February 17 in 2026 (February 15 was a Sunday, and February 16 was Presidents’ Day).

Don’t treat the first copy as final. Corrected 1099s can arrive later.

The sales then flow to Form 8949 and on to Schedule D. So whatever is wrong on the 1099-B carries straight through to your return unless you catch it first.

The boxes and what to check in each

Box	What it shows	What to check
1a	Description of property	Security and share count match your own trade log
1b	Date acquired	Matches the purchase confirmation, above all for shares moved in from another firm
1c	Date sold or disposed	Matches the trade date on the sale confirmation
1d	Proceeds	Agrees with your confirmation, once you know from box 6 whether it is gross or net
1e	Cost or other basis	Present, and adjusted for transfers, reinvested dividends and corporate actions
1f	Accrued market discount	If a figure appears, find out which holding it comes from
1g	Wash sale loss disallowed	Fits your own repurchases in that account
2	Short term or long term, and whether any part is ordinary	Agrees with your own dates for the lot
3	Checkboxes for collectibles and Qualified Opportunity Fund	Reflects what you actually held
4	Federal income tax withheld (backup withholding)	Any amount here makes it onto your return
5	Noncovered security checkbox	If checked, plan to supply basis from your own records
6	Whether gross or net proceeds were reported to the IRS	Tells you how to read 1d
7	Loss not allowed based on the amount in 1d	If checked, ask a tax professional before claiming the loss
8-11	Regulated futures, foreign currency and section 1256 option contracts	Belongs to those contracts, separate from your stock sales
12	Basis reported to the IRS checkbox	Checked means the IRS has your 1e figure
13	Bartering	Should be empty for ordinary trading
14-16	State information	Relevant if you file a state return

Three of these do most of the work for a stock trader. They’re 1e, 1g and 12.

Short term or long term

Box 2 is the broker’s call on whether each sale is short term or long term, measured from the acquisition date it has on file to the date of sale, and it also flags when any part of the gain or loss is ordinary. How the clock runs, and where the line between the two sits, is on the holding period page.

Check box 2 against your own dates. A broker can only count from the date it holds. If a lot came over from another firm with a wrong or missing acquisition date, box 2 can put that sale in the wrong bucket, and you won’t see it unless you compare.

Covered and noncovered shares

Covered securities are the ones whose basis the broker must report. For stock, that means shares acquired for cash in an account after 2010, and stock eligible for the average basis method acquired after 2011; certain debt instruments and options became covered for acquisitions after 2013 or 2015, depending on the type.

Everything else is noncovered. Box 5 gets checked on those lines, and the basis may show as missing or as not reported to the IRS.

Box 12 is the companion check. When it’s ticked, the IRS received the basis in 1e along with your proceeds. When it’s blank, the IRS still has your proceeds, and you’re the one who has to supply a basis you can back up with confirmations or old statements.

What to check before you trust a line

Transferred shares come first. Stock moved in from another broker can arrive with its basis history, or without it. When it arrives without, 1e may be blank or wrong, and the fix is in your own files: the original purchase confirmation, or the old firm’s statements.

Wash sales come next. Brokers track wash sales only within the same account and only for identical securities. So 1g can be exactly right about what your broker saw and still miss a repurchase you made in a different account, at the same firm or another one. The wash-sale window calculator gives you the dates around a losing sale, and from there you can scan your other accounts for buys inside that window. Any wash sale adjustment goes on Form 8949 with code W.

Reinvested dividends are easy to forget. Each reinvestment buys a few more shares at a new price on a new date, and those shares are part of the position when you sell it, so their cost belongs in your basis alongside the original purchase. If a long-held, dividend-paying position was moved between brokers, this is the spot to look hardest at.

Then corporate actions. A split, reverse split, merger or spin-off can change your share count and the basis per share. Make sure 1e reflects it.

One line item, worked through

Say your consolidated statement shows a sale of 100 shares of a made-up company, XYZ. Box 6 says the proceeds are net, box 12 is checked, and box 5 is empty, so it’s a covered lot. You bought in March and sold in August of the same year. You also bought XYZ again, in the same account, shortly after the sale.

Every figure on that line ties to a confirmation. The one thing your broker couldn’t check is whether you also bought XYZ in a second account around the same time. If you did, 1g may be too small. Any further adjustment is yours.

When the form and your records disagree

Start with the paper trail: pull the confirmations for the sale and the purchase and see which side is off. A mistake in what the broker has on file, a wrong acquisition date or missing basis for transferred shares, say, is worth raising with the broker, since a fix there can come through as a corrected form; a difference that comes from something the broker never saw, like a repurchase in another account, is one you handle on Form 8949 yourself. Which route fits your case is a question for a tax professional.

The IRS instructions for Form 1099-B define every box. Two boxes cause most of the follow-up work: box 1g and the wash sale loss disallowed, and carrying each line to the right part of the return, covered in 1099-B to Form 8949. Other tax and recordkeeping answers sit with the rest of the trading questions.