Your 1099-B and your own records will not match exactly, and in most cases that is fine — they are measuring slightly different things. The job is to identify which differences are expected and which indicate a genuine error on one side.

Differences that are expected

The second row is the one that alarms people. You collected $250 in premium and it is not on the 1099-B as income — because the put was assigned, and the premium moved into the shares' basis. It will surface when those shares sell.

Differences that mean something is wrong

Wash sale adjustments you did not expect. The broker flags wash sales within its own account. If several appear that you did not anticipate, your realised loss for the year is smaller than you thought — see the wash sale rule.

Wash sales that should be there and are not. The harder direction. Brokers cannot see across institutions, so a loss at one broker matched with a purchase at another is your responsibility to identify and adjust. Nothing on either 1099-B will hint at it.

A cost basis you disagree with on assigned shares. Usually a partial assignment where the premium was allocated across a different number of contracts than you expected.

Missing transactions. Rare, but not unknown after an account transfer or a corporate action. Worth checking the transaction count, not just the totals.

A workable reconciliation

1. Compare the transaction count first. If the number of closing transactions matches, you are reconciling amounts. If it does not, you are hunting a missing or duplicated event, which is a different job.

2. Compare total proceeds and total cost basis rather than line by line. Most discrepancies show up in the totals immediately and it takes a minute rather than an afternoon.

3. Isolate assignments. Pull every assigned position and check the resulting share basis reflects the premium. This is where genuine errors concentrate.

4. Check the wash sale column. Total the disallowed amounts and confirm they are explainable. Unexplained ones usually mean you repurchased something without noticing.

5. Then go line by line, but only for the subset that did not reconcile.

When they genuinely disagree

The broker is the authority on what happened — fills, dates, assignments, fees — and their reporting goes to the IRS whether you agree with it or not.

You may still be right about the tax consequence in the specific cases the broker cannot see: cross-account wash sales, non-covered basis, and anything involving positions transferred between institutions. Those are legitimately yours to adjust, and they are also exactly the cases where you want professional advice rather than a page like this one.

Making next year easier

Almost all of this becomes trivial with a December year-end close and monthly reconciliation. If you reconciled monthly, the 1099-B check is a comparison of two totals you already trust.

If you did not, the alternative is reconstructing a year from statements in February, which is the situation rebuilding history exists to address.

What can go wrong

Panicking about missing assignment premium. It is in the share basis, by design.

Assuming the 1099-B caught every wash sale. It caught the ones inside that account.

Reading a blank basis as zero. It usually means non-covered, not free.

Line-by-line reconciliation from the start. Compare totals first; most of the work disappears.