Banks provide customers with a pass book that shows all transactions with the bank. The pass book balance may differ from the customer's cash book balance for various reasons. To identify the causes of any disagreement between the balances, the customer must prepare a bank reconciliation statement. This statement reconciles the cash book balance to the pass book balance by listing items that have been recorded in one book but not yet in the other, such as outstanding checks or deposits. Preparing the bank reconciliation statement ensures the customer knows the accurate bank balance.