Write down every transaction, such as deposits, expenses, outgoing checks and ATM transactions, in your check register during the course of the statement month. This is done by writing the amount of each transaction in your register. After writing the amount of each transaction, be sure to subtract from your total balance, so that you can keep a running total of your balance.
Compare your check register with the monthly statement your bank sends you. Cross-check any deposits, interest payments, outgoing checks and ATM withdrawals between the register and statement. Review any automatic bill payments you have established with this account that were not accounted for in your check register and go over any other fees assessed by the bank. These additional transactions may cause a discrepancy between your register and your monthly statement.
Calculate what your balance should be, according to the information in your check register, and compare this balance with your monthly statement. If there is a discrepancy that you cannot account for or your comparison is off by a large amount, contact the bank to investigate whether a mistake was made.