Your 1099-B Doesn't Match Schedule D? Here's How to Find and Fix the Gap

You finished entering your trades, and something is off. The proceeds on your 1099-B say one number, but the total flowing onto Schedule D says another. Maybe your tax software flagged it. Maybe you noticed it yourself while double-checking before you file. Either way, you now have a nagging fear that the IRS is going to send you a letter.

Here is the good news: a mismatch between your 1099-B and Schedule D is almost never a mistake you need to panic about. In most cases it is not even a mistake at all — it is the tax code doing exactly what it is supposed to do. The two documents are measuring different things, and once you understand which number is supposed to match and which one is allowed to differ, the whole problem usually resolves in a few minutes. This guide walks through every common cause, in order of likelihood, so you can find your specific gap and fix it.

Which Number Is Supposed to Match — and Which Isn't

Before you hunt for the "error," you have to know what the IRS actually cross-checks. When your broker files a 1099-B, the IRS receives one critical figure: gross proceeds. That is the total dollar amount you received from your sales. The IRS matches that proceeds figure against the proceeds you report on Form 8949 and Schedule D.

Your cost basis, gain, and loss are a different story. The IRS wants those to be correct, but it does not expect them to equal the raw 1099-B numbers, because the whole point of Form 8949 is to let you adjust the broker's numbers. So:

• Proceeds should match (column d on Form 8949 should tie to the 1099-B). If proceeds don't match, that is worth investigating.
• Cost basis and gain/loss are allowed to differ, and often should, because of adjustments you make in columns f and g.

So the first question is always: is it the proceeds that don't match, or the gain? Ninety percent of the time it is the gain, and the gain is supposed to be different. Here is why.

Cause #1: Wash Sale Adjustments (The Most Common Reason)

If you sold something at a loss and rebought the same or a substantially identical security within 30 days, the IRS disallows that loss under the wash sale rule. Your broker reports the wash sale in Box 1g of the 1099-B, but the disallowed amount changes your gain, not your proceeds.

Here is what happens on paper: your 1099-B might show a $2,000 loss, but $2,000 of it is disallowed, so your Schedule D reflects a $0 loss (or a smaller one). The proceeds are identical; the gain is not. That is a correct mismatch. On Form 8949 you enter adjustment code W in column f and the disallowed amount as a positive number in column g.

If your software imported the wash sale but you also entered it manually, or you double-counted the adjustment, you can get a mismatch in the wrong direction. Check for duplicate wash sale entries first. If you are wrestling with disallowed losses, our full breakdown of how wash sales show up on Form 8949 walks through the column-by-column mechanics.

Cause #2: Accrued Market Discount on Bonds

If you sold a bond you bought below face value, the 1099-B may report accrued market discount in Box 1f. This amount gets pulled out of your capital gain and reported as ordinary interest income on Schedule B instead. The result: your Schedule D capital gain is lower than the raw 1099-B gain, because part of it was reclassified.

On Form 8949 you enter adjustment code D and subtract the accrued market discount in column g. This is one of the sneakiest sources of mismatch because most people never think to look at the bond section of their 1099-B.

Cause #3: Wrong or Missing Cost Basis on Noncovered Securities

For "noncovered" securities — typically anything bought before the broker was required to track basis, transferred in from another broker, or certain older lots — the 1099-B may show $0 cost basis or blank basis in Box 1e. If you enter that literally, your gain looks enormous and your Schedule D total balloons.

The fix is to supply the correct basis on Form 8949 (column e) and, if the broker reported an incorrect basis to the IRS, use adjustment code B in column f with the correction in column g. If your basis is simply missing, our guide to fixing missing cost basis on noncovered securities covers where to dig up the original purchase price.

Cause #4: You're Comparing Summary Totals to Category Totals

Schedule D breaks everything into six categories — short-term Boxes A, B, C and long-term Boxes D, E, F. Your 1099-B lists individual transactions that map to those boxes. A common false alarm is comparing the grand total on your 1099-B against a single line of Schedule D and concluding they don't match.

They aren't supposed to. Line 1b of Schedule D is only short-term covered transactions; line 8b is only long-term covered. Make sure you're adding up the same universe of trades on both sides before you declare a discrepancy. Our explainer on Schedule D line 1a vs line 1b reporting shows exactly which totals belong on which line.

Cause #5: Corrected 1099-B You Didn't Notice

Brokers reissue 1099-Bs constantly — sometimes three or four times between February and April. If you filed or entered your data from the original and a corrected version arrived later, your Schedule D reflects old numbers. Always confirm you are working from the version marked CORRECTED at the top. If an import wiped out adjustments you made, our post on the corrected 1099-B import that erases your data explains how to recover them.

A 5-Minute Reconciliation Checklist

When the numbers don't tie, work through this in order:

1. Isolate proceeds vs gain. Is it the proceeds column or the gain column that's off? If proceeds match, relax — the gain is allowed to differ.
2. Total by category, not in aggregate. Sum short-term and long-term separately, covered and noncovered separately.
3. Look for Box 1f and 1g values. Any wash sale (1g) or accrued market discount (1f) explains a legitimate gap.
4. Scan for $0 or blank basis. Noncovered lots with missing basis inflate the gain.
5. Check for a CORRECTED form. Make sure you're on the latest version.
6. Hunt for duplicates. A double-imported wash sale or a transaction entered twice is the most common actual error.

Nine times out of ten, one of these six lines explains the entire difference.

When the Mismatch Is a Real Error

Sometimes it is a genuine problem. Watch for:

• Duplicate transactions from importing the same file twice.
• A whole account missing — you have two brokers but only entered one.
• Options or futures landing in the wrong section (Section 1256 contracts go on Form 6781, not Schedule D).
• Manual entry typos — a transposed cost basis is easy to make and hard to spot.

If your proceeds genuinely don't match after ruling those out, re-import the raw 1099-B cleanly and rebuild from there rather than patching one line at a time.

FAQ

Does my 1099-B have to match Schedule D exactly?

Only the proceeds need to match. Cost basis, gain, and loss are frequently — and legitimately — different because of wash sales, accrued market discount, and basis corrections you make on Form 8949.

Will the IRS flag me if the totals differ?

The IRS matches reported proceeds. As long as your proceeds tie to the 1099-B and any gain adjustments carry a proper Form 8949 code (W, D, B, etc.), a gain difference won't trigger a mismatch notice.

Why is my gain higher than the 1099-B shows?

The most common cause is a noncovered security with $0 or missing cost basis. Enter the correct basis on Form 8949 and the gain will drop to the right number.

My wash sale loss makes the numbers not match. Is that normal?

Yes. The disallowed loss reduces your deductible loss without changing proceeds. Enter code W and the disallowed amount in column g of Form 8949 — the mismatch is expected.

What if I already filed and then found the mismatch?

If it was a legitimate adjustment (wash sale, market discount) and your proceeds were correct, you likely don't need to amend. If proceeds were wrong or you omitted an account, file Form 1040-X with a corrected Schedule D.

Can a converter tool help me reconcile this?

Yes — a clean extraction of every line from the PDF, with basis, wash sales, and holding periods preserved, removes the manual-entry errors that cause most real mismatches. That's exactly what our tool does.

Bottom Line

A 1099-B that doesn't match Schedule D is usually the tax code working correctly, not a mistake. The proceeds are what the IRS cross-checks, and those should tie out. The gain is allowed to differ — and almost always differs because of a wash sale, accrued market discount, or a cost basis you corrected on Form 8949.

Work the six causes in order, isolate whether it's proceeds or gain that's off, and the gap will name itself. The genuine errors that remain are usually duplicates or a missing account, both easy to spot once you know the legitimate differences are off the table.

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