Why can Form 1099-B proceeds exceed the cash I received?

Because Form 1099-B often reports gross sale proceeds, while the bank deposit may reflect later cash movement.

You need a bridge from gross proceeds to net cash:

1. trade confirmations
2. settlement dates
3. fees or commissions
4. margin or loan repayment
5. withholding
6. transfers to other accounts
7. cost basis

Fresh example:

Avery Stone sells a portfolio and sees 92,600 of proceeds on Form 1099-B but only 88,300 in a bank deposit. The right answer is not to guess. Avery should get the transaction statement and reconcile every movement.

That reconciliation protects against both overpaying and underreporting.